Karina Nigoghossian

Molíria V Dos Santos

Hernane S Barud

Robson R Da Silva

Lucas A Rocha

José M A Caiut

Rosana M N De Assunção

Lubomir Spanhel

Marcel Poulain

Younes Messaddeq

Sidney J L Ribeiro
email: sidney@iq.unesp.br

Orange Pectin Mediated Growth and Stability of Aqueous Gold and Silver Nanocolloids

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Abstract

The role of orange based pectin in the nucleation and growth of silver and gold nanoparticles is addressed. Pectin is a complex polysaccharide found in fruits such as oranges, lemons, passion fruits or apples. It displays smooth and hairy chain regions containing hydroxyl-, ester-, carboxylate-and eventually amine groups that can act as surface ligands interacting under various pH conditions more or less efficiently with growing nanometals. Here, a high methoxy pectin (> 50% esterified) was used as a stabilizer/reducing agent in the preparation of gold, silver and silver-gold nanoparticles. Commercial pectin (CP) and pectin extracted from orange bagasse (OP) were used. Optionally, trisodium citrate or oxalic acid we used to reduce AgNO 3 and HAuCl 4 in aqueous environment. Characterization methods included UV-VIS absorption spectroscopy, transmission electron microscopy, electron diffraction and energy-dispersive x-ray spectroscopy. The results show that under different pH conditions, pectin and reducing agents allow producing various nanostructures shapes (triangles, spheres, rods, octahedrons and decahedrons) often with high polydispersity and sizes ranging between 5 nm and 30 nm. In addition, depending on Ag/Au-ratio and pH, the surface plasmon bands can be continuously shifted between 410 nm and 600 nm. Finally, pectin seems to be a highly efficient stabilizer of the colloidal systems that show a remarkable stability and unchanged optical spectral response even after five years.

Keywords: gold, silver, nanoparticle, pectin. Colloids spanning all visible region were obtained depending on Ag/Au-ratio and pH; Pectin is a highly efficient stabilizer of nanocolloidal solutions for years.

A c c e p t e d M a n u s c r i p t

Introduction

Gold and silver nanoparticles find a range of applications including catalysis, 1 nonlinear optics, 2 opto-electronic devices, 3 sensing, 4 biomedical applications, [START_REF] Yeh | [END_REF] and others. 6 Among several interesting properties, single aqueous suspensions of Au and Ag nanoparticles exhibit fascinating colours. Due the collective oscillation of conducting electrons on the surface of those nanoparticles, strong coupling takes place with specific wavelengths of the incident light, which, in turn, results in absorption and scattering bands in visible region. This phenomenon is widely known as surface plasmon resonance (SPR). Aqueous suspensions of spherical Au and Ag NPs usually display strong SPR bands around 400 and 520 nm, respectively. [START_REF] Kittel | Introduction to Solid State Physics[END_REF] It is worth to pointing up that by tuning the size and shape of those NPs, the control over the optical properties becomes feasible and even predictable. [START_REF] Sharma | [END_REF] Owing the remarkable properties of Au and Ag nanoparticles, when these metals are combined at nanometric scale, yielding alloy Ag-Au compositions, rich and exciting properties can be improved than that of single metal. In fact, the absorption of Au-Ag alloy NPs can be tuned along the visible region by varying the alloy composition. 46 Considering the several techniques used in the preparation of metals NPs since the pioneering work by Michael Faraday in the 19th century, 9 it may be noted that reduction of metal ions precursors in solution-phase remains the simplest and most versatile approach. The fundamental aspects of preparation and stabilization of Au nanoparticles was reviewed by Toma et al. 10 Particular emphasis has been placed on the use of sodium citrate as mild reducing agent in distinct methods such as A c c e p t e d M a n u s c r i p t electrochemical, 11 sonochemical, 12 thermal 13 and photochemical 14 methods. To date, one of the most used solution-phase methods for the synthesis of spherical Au nanoparticles was developed by Turkevich et al. 15 , which is based on the reduction of gold salts (AuCl 3 or HAuCl 4 ) in a boiling aqueous solution containing sodium citrate. Besides reducing agent, citrate ions can also play a role as capping agent by hindering the agglomeration among Au NPs, primarily due the electrostatic repulsion of carboxylate groups. Because the strong affinity between sulfur and gold, ligands displaying the thiol functional group have been extensively used as an effective capping agent of Au nanoparticles, 16 and may also perform controllable fashion on the surface properties of such nanoparticles. 17 In the case of the synthesis of Ag nanoparticles, strong reducing agents, such as borohydride 18 , other than mild ones (i.e. ascorbic acid and citrate [START_REF] Lee | [END_REF] ) have been also employed in solution-phase methods. Several others methods have been proposed

including microwave plasma synthesis, 20 electrolysis of Ag salts, 21 rapid expansion of supercritical solvents, 22 microemulsion, 23 photoreduction of Ag ions 24 and controlled synthesis in organic solutions. 25 Gold-silver alloy nanoparticles can be obtained by simple co-reduction of chlorauric acid and silver nitrate with sodium citrate in aqueous solutions. 46 Green synthesis of nanoparticles are emerging as an alternative to physical and chemical methods. 26 These environmentally benign methods use microorganisms, 27 enzymes, 28 plant extracts, 29 fruits or fruit peels 30 and fungi 31 that act as reducing agents as well as capping agents. In general, the colloidal stability is achieved through functionalization of the NPs surface, preventing agglomeration either by electrostatic repulsion or steric hindrance. To this end, surfactants and polymers with donor atoms or specific chemical groups 32 are highly desirable to develop a reliable protective capping. For example, poly(vinylpyrrolidone) (PVP) is one of the most commonly neutral synthetic polymer studied as stabilizer in the synthesis of metallic nanoparticles. 33 The interaction between PVP molecule towards the metal atoms of the nanocrystal surface occurs through affinity of oxygen and nitrogen donor atoms present in the amide carbonyl group of PVP molecule. For instance, the large skeletal chain of PVP provide steric hindering against aggregation among the nanoparticles. Pectin and other heteropolymers from natural sources such as gum arabic, 34 carrageenan, 35 chitosan 36 and heparin 37 have also similar properties that allow them accomplish as reliable stabilizing agents for metal colloidal systems by forming a protective coating that prevents eventual precipitation. 38 The condensation kinetics, shape tuning and long term stability of colloidal metal particles depends strongly on the geometry and chemistry of metal precursors, templating-, stabilising-as well as reducing agents and solvents.

Pectin is a complex polysaccharide with smooth and hairy chain regions and is found in almost all plants. The main sources with commercial interest are the apple pomace, peel of citrus fruits and of passion fruit. [START_REF] Ranken | Manual de industrias de los alimentos[END_REF] The composition of the pectin molecule depends on its source. For example, pectin from citrus fruits contains less neutral sugars and smaller molecular size compared with apple pectin. [START_REF] Hamman | [END_REF] Pectin has a complex structure (Figure 1) mainly composed of (1→4) linked α-D galacturonic acid esterified units. The acid groups along the chain are esterified with methoxyl and Ag + and minimize the chemical potential in order to stabilize Au-Ag alloy nanoparticles.

The presence of methoxyl groups and carboxyl groups in pectin is a favorable factor for using this material in some applications like the stabilization of colloids.

The main goal of this work was to use Pectin extracted from orange bagasse presenting high esterification degree (76%) in the preparation of gold, silver and gold-silver nanoparticles. Several different properties can be envisaged and in a previous contribution, singlet oxygen generation in riboflavin water solutions was observed to be enhanced by pectin stabilized silver nanoparticles. 42

Experimental

Reagents and apparatus

Commercial pectin (CP Kelco brand) type Genu 105 with esterification degree of 67% was used as a sample standard. HAuCl 4 , AgNO 3 , oxalic acid, trisodium citrate and methyl orange (Sigma Aldrich) were used.

The UV-VIS absorption spectra of the colloids were measured by using a

Varian CARY 5 spectrophotometer. High resolution transmission electron microscopy (HRTEM) images and electron diffraction analysis were performed detector was used to map a single particle of gold and silver.

Extraction of pectin from oranges

Pectin was extracted from the mesocarp of oranges under acid hydrolysis. The triturated orange mesocarp was heated in water (70 °C) for 10 minutes to inactivate endogenous cell wall degrading enzymes, such as poly(galactorunase).

The solid was separated and then dried in a ventilated oven at 35 °C.

The dried raw-material was suspended in distilled water (solid-liquid ratio 1:10, w/v) and HCl 0.1 M solution was added to adjust the pH between 1.5-3.0. The mixture was continuously stirred at 60 °C for two hours ant then filtered. Ethanol was added to the filtrate in order to precipitate the pectin. The precipitate was dried by lyophilization.

The esterification degree (ED) of orange pectin (OP) was determined by potentiometric and conductometric titration based on the method described by Bochek et al. [START_REF] Bochek | [END_REF] In a first step, an aqueous solution of OP 0.05% w/w was titrated with NaOH 5mM to determine the number of free carboxy groups of The total number of the carboxyl groups is equal to the sum of the free and esterified groups. The ED is given by the ratio between the content of carboxylic groups esterified and total.

Preparation of silver, gold and gold-silver nanoparticles

The following solutions were prepared: HAuCl 4 1mM and AgNO 3 1mM. Pectin extracted from orange (OP) and commercial pectin were used to prepare the nanoparticles under the same conditions. An aqueous solution of pectin 0.5% (w/v) was prepared under stirring for two hours at 40 ºC. Solutions of sodium citrate 0.1 M and oxalic acid 0.1 M were prepared as reduction agents.

Gold nanoparticles

In a typical synthesis, OP (1 mL) and HAuCl 4 (3mL) solutions were added to distilled water (25 mL) under stirring. The resulting solution was heated at 80 ºC,

Silver nanoparticles

Silver nanoparticles were prepared with a similar methodology used for the synthesis of gold nanoparticles mentioned before. Only trisodium citrate was used as reducing agent.

Pectin as reduction agent of gold

OP could be used as reducing and stabilizer agent of Au NPs. OP (3 mL) and HAuCl 4 (3 mL) solutions were added to distilled water (24 mL) under stirring. The solution was kept boiling until colour change, then immediately removed from the heat.

On the course of the reaction, several colours changing took place on the aqueous solutions, whose characteristic extinction bands were carefully monitored by UV-Vis spectrophotometry.

Au-Ag alloy nanoparticles

Au-Ag alloy nanoparticles were prepared by modifying the Ag:Au molar ratio. In this case, only trisodium citrate was used as reduction agent. The solutions of OP (1 mL), AgNO 3 and HAuCl 4, whose Ag:Au volume ratio was set to 3:1, 1:1 or 1:3, were added to distilled water. The final volume was 30 mL. They were heated at 80 ºC and trisodium citrate solution (1 mL) was added. The solution was kept boiling until colour change, then immediately removed from the heat.

A c c e p t e d M a n u s c r i p t

The different routes used for the preparation of colloidal systems are presented in Figure 2.

Results and discussion

The pectin extracted from orange was characterized by potentiometric and conductometric titrations to determine the esterification degree (ED) of poly(galacturonic) acid. The equivalence point was determined from the titration curves shown at The optical properties of gold and silver nanoparticles depend strongly on their size and shape. It is well known that resonance of the incident light with surface plasmons is the main mechanism for the appearance of colours. Aqueous suspensions of Au NPs are red for nanoparticles in the range between 2 and 10 nm.

They display violet colour for larger sizes of nanoparticles. 44 In fact, the formation of nanoparticles in solution can be easily followed by using UV-VIS-NIR spectroscopy. 45 The products obtained in this work displaying different colours are pictured in A control sample containing Au NPs prepared in the absence of pectin was violet in colour, but the system showed up not stable. Aggregation of particles was observed around 30 minutes after the introduction of reducing agent mostly due to the lack of a stabilizing agent.

Figure 5a shows UV-VIS spectra. Ag NPs suspension showed a characteristic peak at 409 nm. Absorption spectra of Au NPs showed a broad band centered at 522 nm for samples prepared with trisodium citrate as reducing agent. For samples Au-Ag alloys particles are formed in preparations where Au and Ag ions are reduced simultaneously by trisodium citrate in the same solution. The alloy formation is confirmed from the fact that the optical absorption spectra show only one plasmon band. 46 Two bands would be expected for the case of a mixture of single gold and silver nanoparticles, 47 or Au@Ag core-shell nanoparticles. 48 There is a shift of the peaks along the wavelength according to the changing concentrations of silver and/or gold. A linear dependence of the plasmon absorption maximum on the composition of the nanoparticles is shown in Figure 5b. Increasing particle size and/or aggregation usually leads to red shift and broadening of the plasmon band. These effects can be ruled out with aging of the suspensions prepared here, as may be observed in the UV-Vis spectra (Figure 6).

In fact colloidal suspensions remained stable from the time of preparation of the solutions up to five years. Moreover, it is worth to outline that Au NPs prepared in the presence of OP showed the same optical and morphological characteristics of those prepared with commercial pectin. Electron diffraction analysis was performed to determine the structure of the particles (Figure 10). Electron diffraction pattern for Au NPs reduced by trisodium citrate (Figure 10a) presented interplanar spacings of 0.2353 nm, 0.2025 nm, 0.1446 nm and 0.1234 nm. For the Ag-Au 1:1 and Ag-Au 1:3 alloy NPs (Figures 10b and10c), the interplanar spacings were 0.2350 nm, 0.2038 nm, 0.1450 nm and 0.1230 nm. In all cases, the calculated interplanar spacings corresponded to the (111), ( 200), ( 220) and (113) planes that confirm a face-centred cubic structure of pure Au NPs reduced by trisodium citrate and alloyed Ag-Au alloy NPs. 49 A c c e p t e d M a n u s c r i p t

Conclusions

In this contribution, the role of orange based pectin in the nucleation and growth of silver and gold nanoparticles was addressed. The conditions for the preparation of Au-Ag colloids with different colours spanning the entire visible range by using pectin as a stabilizer were well determined. Nanocolloids so prepared were

A

  c c e p t e d M a n u s c r i p t A c c e p t e d M a n u s c r i p t

  A c c e p t e d M a n u s c r i p t Graphical Abstract (GA) Highlights Pectin from orange was used as stabilizer of Ag, Au and Ag-Au nanoparticles; Sodium citrate, oxalic acid or pectin were used as reducing agents;

A c c e p t e d M a n u s c r i p t

A c c e

  p t e d M a n u s c r i p t groups on natural materials. It presents a rate of 1-4% of L-rhamnose (Rha) units linked by α-(1 → 2) that interrupt the main chain.41 Pectin chains contain hydroxyl-, ester-, carboxylate-and eventually amine groups that can act as surface ligands and interact under various pH conditions more or less efficiently with growing nanometals.

Figure 1 .

 1 Figure 1. (A) Complex Pectin structure containing fragments of linear helical

  A c c e p t e d M a n u s c r i p t using a HRT JEOL3010 URP equipment operating at 300 kV and a Philips CM 12 microscope equipped with a super-twin lens (C s = 1.2 mm) and a 9800 EDX analyzer (Helmholtz Zentrum Berlin) being operated at 120 kV . Samples were prepared by placing a drop of nanoparticles suspension onto the surface of a Lacey formv/carb 300-mesh copper grid, followed by evaporation of the solvent. A fieldemission gun transmission electron microscope (FEG-TEM) JEM 2100 operating at 200 kV and equipped with an energy dispersive x-ray spectroscopy (EDS)

A c c e

  p t e d M a n u s c r i p t poly(galacturonic) acid. Once determined the free carboxy groups, NaOH solution (40 ml) was added to the pectin solution in order to saponify the methyl ester groups of the polymer. Afterwards, excess of NaOH was titrated with HCl 5mM.

and the reducing agent ( 1

 1 mL of trisodium citrate or oxalic acid solutions) was added. The solution was kept boiling until colour change, then the heat source was immediately removed. In a second procedure the pH of the resulting solution was set to 11 by adding solution of NaOH 0.1 M. Afterwards, it was heated up to 80 ºC under vigorous stirring and oxalic acid solution (1 mL) was introduced. The A c c e p t e d M a n u s c r i p t solution was kept boiling until colour change, then immediately removed from the heat.

Figure 2 .

 2 Figure 2. Schematic illustration of the synthesis of Au, Ag and Ag-Au alloy

Figure 3 .

 3 Pectin was obtained with ED of 76 %. The isoelectric point (IEP) was located around pH 5, implying that below this pH the polymer chains are positively charged and strongly interacting with the nanoparticles. On the other hand, above pH 5 the negatively charged chains act as steric stabilizers A c c e p t e d M a n u s c r i p t and exhibit an electrostatic repulsion towards negatively charged condensing nanoparticles. Thus, this situation favours the growth of particles with larger sizes.

Figure 3 .

 3 Figure 3. Potentiometric and conductometric titration curves collected on aqueous

Figure 4 .

 4 Figure 4. The samples form translucent solution with yellowish colour for aqueous

Figure 4 .

 4 Figure 4. Different colours of aqueous solutions obtained for Ag NPs (a), Ag-Au

A c c e

  p t e d M a n u s c r i p t prepared with oxalic acid, the absorption maximum was observed to depend on the pH (540 to 570 nm).

Figure 5 .

 5 Figure 5. (A) Extinction spectra recorded from aqueous solution of Ag NPs (a),

Figure 6 .

 6 Figure 6. Extinction spectra recorded from aqueous solution at the time of

A c c e

  p t e d M a n u s c r i p t TEM images, shown in Figure 7 indicate that Au and alloyed Ag:Au alloy NPs were successfully obtained. The use of different reducing agents allowed the fabrication of various nanostructures shapes (triangles, spheres, rods, octahedrons and decahedrons) and sizes (5 nm -30 nm).

Figure 7 .

 7 Figure 7. TEM images of OP capped Au NPs (A, B, C) and alloyed Ag:Au = 1:1

Figure 8 shows

 8 Figure 8 shows TEM images obtained for Au and Ag-Au alloy NPs prepared with

A c c e p t e d M a n u s c r i p tFigure 8 .

 8 Figure 8. TEM images and size distributions of the following NPs: Ag (a), Ag-Au

Figure 9 shows

 9 Figure9shows TEM images and size distribution of nanoparticles prepared using

A c c e p t e d M a n u s c r i p tFigure 9 .

 9 Figure 9. TEM images and size distributions of Au NPs reduced by pectin (A),

Figure 10 .Figure 11 .

 1011 Figure 10. Electron diffraction pattern of Au NPs reduced by trisodium citrate (A),

A

  c c e p t e d M a n u s c r i p t

Acknowledgements

We thank the FAPESP and CAPES (Brazilian research funding agencies) and University of Rennes 1 (UMR CNRS 6226) for financial support. The Electron Microscopy Laboratory (LME) of the Brazilian Synchrotron Light Laboratory (LNLS) along with Ms. U. Bloeck from the Helmholtz Zentrum Berlin are acknowledged for TEM-HR analysis data. L.S. is on leave from the University of Rennes at the Central European Institute of Technology, Brno (Project CZ.1.05/1.1.00/02.0068).

A c c e p t e d M a n u s c r i p t observed to be stable for years remain stable with the same colour and no aggregation.

The formation of Ag-Au alloy nanoparticles is supported by the TEM-EDS results, and also by the absorption spectra presenting only one plasmon absorption band, the shift of the band proportional to the metal molar ratio and the absence of a core-shell structure on TEM images.


Philippe Tigréat
email: philippe.tigreat@telecom-bretagne.eu

Reading is an automated process. One of the remarkable human abilities is that we can read even partially erased or hidden words. We carried out a study on written word recognition in order to decipher how much information is required at least to identify a word. Experimental software was designed in C++ language to measure the amount of information in pixels and reaction time. The results showed we could identify words at a very low display rate and suggest that prior knowledge on the category of words play a mediating role in written word recognition.

Introduction

As soon as we see something written such as a signboard, we automatically read it.

Reading is, indeed, an automated process wherein two types of processingthat is, bottom-up and top-down processinginteract [START_REF] Treiman | Handbook of Linguistics[END_REF]. This automation of reading has been considerably proven namely by the Stroop effect [START_REF] Stroop | Studies of interference in serial verbal reactions[END_REF] that has been replicated over 700 times [START_REF] Macleod | Half a century of research on the Stroop effect: an integrative review[END_REF]. When we read a word we have never seen, the main thing of reading process occurs in a bottom-up way; top down processing plays a key role in reading words we know and partially erased or hidden words as well. In the latter case, how much information at least do we need to recognize a word? Some studies on written word recognition have been carried out from different angles such as contrast energy [START_REF] Pelli | The remarkable inefficiency of word recognition[END_REF] and letter fragmentation [START_REF] Jiang | The human visual recognition ability for incomplete letters[END_REF][START_REF] Jiang | Quantification of the human ability to identify fragmented letters through visual interpolation[END_REF]. Is recognition of a partially presented word easier when we know its category? To answer these questions, we designed experimental software in C++ to measure the amount of information in pixels necessary for written word recognition and verify a possible category effect.

* Corresponding author

Experiment

Paradigm and Stimuli

Our experiment consisted in recognizing pixelated words that were partially presented.

It had three sessions, and each of them corresponded to a categoryliving things (plants and animals), animals and mammalswith twenty 4-to 9-letter French words.

The lexical stimuli were selected from the French lexical database Lexique 3.80. Each session had a group of ten high frequency words and that of ten low frequency words.

Across sessions, word frequency was maintained equal on average for both lists (see Table 1). The number of words with different lengthsshort for 4-to 5-letter words; medium for 6-to 7-letter words; and long for 8-to 9-letter wordswas balanced as well. Ten words were supplementarily chosen for a training test. Each word was pixelated; only the pixels composing letters, i.e. black pixels, were counted in summation of the amount of display rate. The pixels of each word displayed and the order of words were random in each round. The initial display rate was 0.25%, then 0.5%, and increased following an increment of 0.5% as shown in Figure 1. The order of sessions was balanced. This experimental software was built using the C++ programming language along with the Qt library.

Participants

Twenty-three volunteers working at Télécom Bretagne signed an informed consent form and participated in this experiment. They were 14 males and 9 females whose mean age was 39 years 5 months. All were native French speakers with normal or corrected-tonormal vision. Eleven persons were not informed of the categories (1 st group) and the other twelve persons were in the informed (2 nd ) group. Courier, all letters were in uppercase, and each letter of words was displayed in a 77×70 pixel frame. Allowing for the angle of view for reading (5° to 10° for each eye), the longest words were no more than 21.83cm long.

The experiment took place in a quiet room wherein the screen and the keyboard were placed in front of the participant. The distance between the screen and the participant was 103cm. When the experiment started, the instructions were displayed on the screen, accompanied by the experimenter's verbal explanation. When the participants felt ready, they pressed the enter key to start each session. A fixation cross appeared for 500ms, followed by a pixelated (target) word for 350ms, then a white screen for 2000ms (see figure 2). The participants were asked to read each word displayed on the screen. In the case that they did not identify the word displayed, they let the sequence pass. As soon as they recognized the word, they pressed the space bar to stop the sequence, and then typed the word they had just recognized. Typing was not time-limited; only reaction time (RT) was measured. When they finished typing the word, they pressed again the space bar to resume the sequence. When the participants thought that they made a mistake while typing, they pressed the backspace key to erase the letters they had just typed in order to restart typing.

Figure 2. Configuration of each word presentation in the experiment

Results

The incorrect answers due to motor or orthographic errors were reclassified as correct answers. Motor errors are when the participant typed one of the letter keys right around the correct letter key. The words unknown to each participant were excluded from the data. We carried out multi-factorial ANOVA analyses considering only the correct answers.

As shown in Table 2, the incorrectly identified words were recognized at a significantly lower display rate than the correctly identified words (P<0.0001) in both groups.

Reaction time was shorter when words were correctly identified (P=0.0008 The group that was not informed of the categories (1 st group) was significantly slower (P=0.0091) than the informed group (2 nd group), see Figure 3. No significant difference was observed between the two groups in terms of display rate, see Table 3. In order to determine the minimum amount of information for written word recognition, correct and incorrect answers of all participants were compared at each display rate (%).

Significant difference between these two types of answers indicates the minimum amount of information necessary for written word recognition, i.e. when the number of correct answers becomes significantly greater than the amount of incorrect responses.

Most participants started correctly identifying words at 1% (see Figure 4).

Discussion

The aim of our study was to measure the minimum amount of information necessary for written word recognition and to verify a possible category effect. Comparison between correct answers and incorrect answers showed significant differences in favor of correct answers in terms of reaction time, and of incorrect answers with regard to display rate.

This negative interaction could be explained as follows: at lower display rates the participant has less information, this lack of information would increase the time necessary for the participant to respond.

In group comparison, no significant difference was observed in display rate. As to reaction time, the second group that was informed of categories responded significantly more quickly. It could be argued that knowing the contextthe category in our studyplays a moderating role and hence facilitates word recognition by accelerating reaction time without changing the minimum amount of information (display rate) necessary for word recognition. This facilitation is due to the well-known top-down effect [START_REF] Wheatley | Automatic Priming of Semantically Related Words Reduces Activity in the Fusiform Gyrus[END_REF][START_REF] Neely | Semantic priming effects in visual word recognition: A selective review of current findings and theories[END_REF] in the scientific literature of psycholinguistics. The orthographic errors that the participants made in our study prove the top-down effect in recognition processes of partially presented pixelated words. When they got a clue of the target word, they used their orthographic knowledge rather than a "copy and paste" process. This top-down effect proves the existence of category/context effect in our experiment.

The human ability to read correctly partially erased words is processed by dint of a combination between top-down and bottom-up processing in reading [START_REF] Treiman | Handbook of Linguistics[END_REF].

We thus tried to measure the minimum amount of information needed to recognize partially presented pixelated words. The result showed that the display rate at which the participants started giving significantly more correct answers than incorrect answers was 1%. This amount of information only takes account of black pixels. Do white pixels constituting blanks in letters really provide no information? If they contain some information, is it equivalent to that of black pixels? What role do pixel positions play in recognition? In the face of these thorny questions, we chose to consider only black pixels in the present study. The minimum amount that we found may therefore not be very precise, but it may be quite close to what we have been seeking.

Conclusion and further research

The minimum amount of information necessary for written word recognition was measured by means of the proportions of black pixels displayed. It was shown that the minimum amount was 1% of all black pixels of a word. Knowing the category of words in advance of each session helped the participants respond significantly more quickly.

However, having this top-down influence did not diminish the display rate necessary to recognize words. This temporal enhancement is due to more information available, i.e.

better top-down processing (words vs. a particular category of words). The category/context effect in our study is therefore directly linked to top-down effect.

As mentioned in the discussion part, it will be necessary to compensate the defect by means of further studies. It is fundamental to determine the value of white pixels and the importance of pixel positions. Since some same words were identified at very different display rates, only the positions of pixels would be the main determinant. It is thus required to discern pixels that are more important for recognition, if any. With this aim in view, an analysis is ongoing to calculate information density of each pixel. If this information density turns out to be important for word recognition, it will give rise to a new experiment using only pixels crucial to recognition at a very low display rate and/or using pixels shared by most letters at a very high display rate. In company with information density, pixel locations and distances will be taken into account as well.

The results will confirm or invalidate our hypothesis that the position of pixels is central to written word recognition.

Figure 1 .

 1 Figure 1. A pixelated sample word 'JAGUAR'

Figure 3 .

 3 Figure 3. Group effect in reaction time (RT)

  ).

		%	RT
	Correct answers	2.7826	864.2748
	Incorrect answers	1.9084	929.3790
	P	<0.0001	0.0008
	Table 2. Display rate (%) and reaction time (RT) in both groups

Table 3 .

 3 Group comparison and multi-factorial ANOVA for reaction time

		%	RT		F	P
	1 st group (not informed) 2.8202 876.2864	Group	6.81	0.0091
	2 nd group (informed)	2.7360 852.8486	Category	3.33	0.0362
	P	0.2525	0.0091

Acknowledgement

This project was funded by the European Research Council (NEUCOD, ERC-AdG2011 290901).


Gabriel Galvez-Behar

L Hilaire-Pérez

Albin Michel

; B Z Khan

PATENTS AND THE MARKET FOR TECHNOLOGY IN THE EARLY 19TH CENTURY FRANCE

Introduction

From an economic perspective, the transferability of intellectual property rights is one of their essential attributes. Allowing optimal allocation of resources and promoting therefore the use of these rights, transferability strengthens the use of the invention itself, by attracting capital, whose inventor does not necessarily benefit, and by making the invention a commodity. This fundamental feature is probably one of the foundations on which markets for technology are based.

Markets for technology have already been the subject of historical works 1 . Paradoxically, although the French patent laws were among the oldest ones in the emerging industrialized world, the analysis about the use of patents in the market for technology is not really complete 2 . If the institutional framework or the intermediaries have been considered, the assignments themselves have not been studied from a quantitative perspective.

Since the Ancien Régime, however, the privileges for inventions could be sold in France. The 1791 French patent laws allowed the patent holders to sell their rights. However, to be valid, such a sale had to be made before a notary and be registered in the prefecture. From the 1820s, these registrations were published in the Bulletin des lois. This provision was extended by the 1844 patent law and was always implemented. Thanks to this legal requirement, we have the opportunity to analyze an uninterrupted source about all these transactions during the whole 19th century.

Our paper focuses on the first half of the 19 th century in France from the adoption of the 1791 patents laws to the 1844 reform. First, we review the French patent system. Next, we focus on the institutional requirements about the transfers of patents and we discuss the sources. Next, we analyze the assignments occuring during this period and we compare them with the data available about all the patents issued during the early 19th century.

Inventing a patent system

Admittedly, many of the problems relating to the right of the inventor appeared long before the French Revolution. The royal declaration on privileges for inventors in 1762 was a moment of drawing a new conception of privileges, which depended on the strong debates about the economic regulation. As demonstrated by Liliane Hilaire-Pérez, the invention was the subject, early in the 18th century, to an administrative mobilization, which was amplified by the spread of the encyclopédisme 3 . Thanks to this process, the inventor acquired a new dimension: principles of natural law legitimized the claims of intellectual property, already widely perceived by Denis Diderot for instance 4 . At the very end of the Ancien Régime this trend became stronger. In the 1780s, even as the exclusive privilege was the subject of considerable criticism, many agreed that transitional monopolies could be granted to inventors. Inspired by the British patent system, the French royal administration facilitated the granting of privileges for inventions and made procedures of prior expertise easier. In return, it required from privileges holders the deposit of their inventions in order to promote the development of industrial knowledge. Recognition of the natural right of inventors, issuing temporary privileges to reward them and to allow the access to the market and the disclosure of inventions were the three features of a model, which appeared even before the Revolution.

The Revolution of inventors (1791)

The Revolution accelerated this process. The first feature of the revolutionary genesis of the patent was the strong lobbying of inventors' associations in the development of the new patent law. At the end of the Ancien Régime some associations devoted to the promotion of art and science had came to light. The Revolution promoted the development of new societies defending inventors' rights. One of them, the Société des inventions et des découvertes presented in September 1790 a petition to the Comité d'agriculture et du commerce, demanding a patent law in France 5 . Stanislas de Boufflers was nominated as a rapporteur 6 . He presented his Rapport sur la propriété des auteurs de nouvelles découvertes et inventions en tout genre d'industrie on December 30, 1790. Boufflers was clearly inspired by Diderot's arguments, pointing out that « if there is a genuine property to a man, it is his thought. » 7 For him, the inventions were considered as inventor's products, which property has to be secured. Boufflers proposed a bill, which was based on these principles, but also on the idea of a contract between inventors and society. As long as the inventor kept his invention secret in his own mind, he remained its absolute master. However, disclosing it to take effectively advantages from it, he took the risk to be dispossessed. If the inventor's protection was legitimate, it had a strong price because of the particular nature of this immaterial object. In order to compensate the society for this cost, the inventor must not only renounce the secret by providing an exact knowledge of his invention but it also must give up its rights after an interval of time. Because this right was considered as the result of a natural one, patent examination by the government was out of the question. Whether conducted by scientists or by members of corporations, such an examination was, in Boufflers' eyes, necessarily arbitrary because it established « a court judging for things that do not yet exist. » 8 For him the government was unable to take a decision about the usefulness of new things, which could only be labeled by the public opinion.

On 7 th January 1791, Boufflers' bill became the first patent law in France and it was immediately contested by those, who considered that patents were useless privileges. Again the action of the Société des inventions was essential. For these inventors, the patent law tended precisely to make an end with the privileges system because inventor's rights were 5. G. GALVEZ-BEHAR, « Genèse des droits de l'inventeur et promotion de recognized as a natural and "inalienable human" one. Thanks to a strong lobbying, a second patent law, confirming the first one, was adopted in May 1791. In order to draw a strict distinction from the old privileges, the patents were now called "brevets d'invention".

A slow and difficult diffusion

The adoption of the French patent laws in 1791 did not cause any upheaval in the delivering of patents. On the contrary, in a first instance, granted patents were as numerous as applications for privileges at the end of Ancien Régime. In the 1780s 16 applications were filed on average each year to the Comité du commerce 9 . Between 1791 and 1801, 15 patents were delivered each year. The number of patents continued to stagnate until the reign of Charles Xth (1824-1830), when it begun to rise rapidly. Thus, for nearly thirty years, the patents were slowly being adopted, which was concentrated in certain industries and in certain areas. In fact, between 1791 and 1803, mechanical, textile and chemical industries concentrated almost half of the patents (respectively 21%, 19% and 7.5 %). In addition, the weight of Paris and its region appeared overwhelming. In the first years of enforcement, nearly three quarters of patents were taken in the department of the Seine ; in the 1830s as Parisian patents represented less than half of the patents granted 10 . Many reasons contribute to explain this slow development. The first one was probably the cost of patents, which was prohibitive. The patent tax was indeed very expensive : for a 15 years patent, it raised 1500 francs whereas worker's wage was 1,5 francs a day in the early 19th century. Added to other administrative costs, this tax made the French patents inaccessible to many inventors. Besides, the heaviness of litigation was another stumbling block. A member of the Conseil général des manufactures said in 1819 that « the prosecution, that the patent holders are obliged to undertake, frighten many artists, especially in the departments, and prevents them from taking patents.» 11 Four years later, Francoeur, professor at the Faculty of Sciences in Paris, denounced not only the high cost of such litigations but also the leniency of the courts, asking them to be as severe as in England towards counterfeiters [START_REF]Dictionnaire technologique ou nouveau dictionnaire universel des arts et métiers[END_REF] .

Mistrust

Because of such shortcomings, the patent laws were subject to some adjustments. An act of September 20, 1792 prevented from patenting financial methods. But more radical projects also appeared trying to undermine the 1791 patent laws. In 1796, it was asked that patents were issued only after a "mature consideration" [START_REF] Eude | Rapport au Conseil des Cinq-Cents[END_REF] . This apparent challenge to the principle of non-examination of patents caused, in turn, so strong reactions that the project was abandoned. In 1811 the Conseil général des fabriques et des manufactures intended to reform the patent laws but its work remained unsuccessful. In 1814, the issue was raised again, without further success. In 1821, the same commission addressed the issue again and again things were dragging on until the Minister of Trade revived the project in 1826 [START_REF]Meetings of[END_REF] . Patents becoming more and more numerous, the Minister of Trade, the Comte de Saint-Cricq convened in October 1828 a commission to prepare a new patent law. But the reform only came in 1844.

Contrary to its philosophical foundations, the revolutionary patent laws provided a protection only to inventors who were able to pay the cost. This feature could suggest that the French patent system was not democratic but other arguments have to be taken into consideration. The fact that rich industrialists could be reluctant to take patents because of its inefficiency intimates that the slow diffusion of patents was based on factors different from social ones. On the other hand, the refusal of preliminary examination proves that the revolutionary patent law was not based on the same philosophy than the system of privileges, which had begun to evolve at the end of Ancien Régime. Moreover, the best proof of the revolutionary rupture is certainly the fact that the French patent system was not abolished despite the critics. It responded to real needs : protecting inventions and, more particularly, allowing their assignment without any governmental intervention.

A new institutional framework for the market for technology

During the Ancien Régime, it was already possible to sell his privilege on invention or to make somebody else benefit it. Such transfers, however, had to be included in the initial grant of the privilege or to be later authorized by the King. Sometimes it is true, the sale occured before authorization, what suggests the gap between the dynamics of the market for technology and the slowness administrative procedures [START_REF] Hilaire-Pérez | L'invention technique au siècle des Lumières[END_REF] . In 1762, the Déclaration royale concernant les privilèges en fait de commerce said that the privileges granted to inventors were personal rewards. If privileges could be assigned freely to children and grandchildren of patentees during their own life, selling privilege to any other people had to be authorized by the royal administration. So, during the Ancien Régime, transferring privileges was, theoretically at least, under the control of the royal administration like the privileges themselves.

Creating transferability

With the 1791 patent laws emerged a new paradigm and patent assignments were at stake. Article 14 of the first 1791 patent law (7th January 1791) stated as follows:

"Any patent owner shall be entitled to form establishments throughout the Kingdom, and even to allow other individuals to put it into practice and to use its resources and processes; and in any case, it may use it as a movable property"

This change to the old rules was fundamental. Preliminary authorization was no longer necessary. Considering the patent as "a movable property" the new law makes a priori possible any purpose related to personal property and this assimilation was reinforced by tax rules [START_REF]Supplément à la troisième édition du dictionnaire du notariat: A-D. Tome premier[END_REF] . To some extent, a new institutional framework for the market for technology was created and the Act of 25 May 1791 clarified things about the practice of this right. Article 15 provided that selling a patent required an agreement guaranteed by a notary. Besides both parties had to declare the assignment to the Directoire -later the prefecture -in their own department. Such a process was important. If it was not enforced, it did not lead to the cancellation of the sale itself, much less the patent, but if the buyer wanted to pursue any infringer, he had to respect such a registration procedure [START_REF] Regnault | De la Législation et de la jurisprudence concernant les brevets d'invention, de perfectionnement et d'importation[END_REF] .

As ambiguously as for the patents themselves, patent assignments has to be known. In 1794, the revolutionary government had created the Bulletin des lois in order to publish all the general acts, including the patents. On 5 Vendemiaire an IX (27 th September 1800), an order of the Premier Consul made this publication compulsory every three months in the Bulletin. But if the delivered patents were actually published, it may not be the case for the sold ones. In 1824, however, the Bulletin began to publish the assignments within each delivering patent decree and from April 12, 1842, sold patents were published independently of granted ones. They will be throughout the 19th century.

The 1844 reform reinforced the 1791 provisions about transferability. Even if the notion of "movable property" was not mentioned anymore, article 20 of the 1844 patent law indicated that each patentee could sell the "property of his patent". The same administrative requisites as the previous ones were expressed : the contract had to be made with a notary and to be registered at the prefecture. Every three months, these transfers should be published in the Bulletin des lois. However the new patent law added some provisions. First, the assignment had to be registered in the department where the agreement had been concluded. Second, the transfer necessitated to pay the whole cost of the patent. In a case of a 15 years patent, this represented a 1 500 francs spending (minus the fees already paid). Third, the 1844 patent law pointed that a patent buyer could automatically take advantage from the improvement certificates, which could have be delivered before or even after the sale.

Even if assimilating patents to property was strongly debated in the 1840s, patents were considered as transferable assets 18 . The intervention of a notary, which permitted to have legal and genuine contracts, the procedure of registration, which looked like the one for the land Registry, and even the fiscal provisions made the patents comparable to movable goods. But, of course, a major difference remained : invention were not only immaterial goods but also uncertain ones. Because of the absence of official preliminary examination, French patents were, in a sense, only defined by themselves. Since 1800, they were indeed issued sans garantie du gouvernement ("without governmental guarantee", the famous "SGDG"). As a consequence, the risk of having a non-valid patentbecause of default of novelty, for instance -was only supported by the patentee. Such a feature had some implications for the patent transfer. Selling a patent could be void if the patent itself was invalidated by a 7/18 court. In the French patent system, since no state administration took the responsibility to give the patent a mark of recognition, the value of a patent depended only on the confidence of stake-holders or on a court decision : patents gave, in fact, highly risky rights.

Fragmented sources

The implementation of these administrative rules left traces, which are essential sources to think about the market for technology in 19 th century France. These sources are, in fact, multiple and heterogeneous. The first set consists of the original patent files stored at the French patent Office (INPI). Unfortunately most of the administrative correspondence relating to 19 th century patents was removed and the records relating to the life of patents have apparently not been preserved. However some files contain some information about the sale of patents. For example, the file from the 1842 Gay-Lussac' and Lacroix' application about a sulfuric acid manufacturing process contains a letter from the Manufacture royale des glaces de Saint-Gobain informing the Minister of the sale of patent 19 . The retrospective catalogs published in 1826 and in 1842 include also some information on patent assignments but only for patents still in force at the moment of their publication 20 . At last, the database, which has been established by the INPI about 19 th century French patents, contains also important information: for the period 1791-1844, 644 patents are labeled as assigned 21 . The problem is that such records are not homogeneous. Some assignments mentioned in the INPI database are not in the catalog 22 . Actually, the only continuous source about assignment are those published from 1824 in the Bulletin des lois, which gives, despite changes over time, some details about :

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• The kind of transfer. "Total transfer" (when all the patent rights are assigned) have to be distinguished from "partial" ones (only some rights are sold in a specific area for instance), "licenses", "property changes" (such as when someone one inherits a patent).

•

The place where the transfer was registered. According to the 1791 patent law, the transfer has to be registered in the department of each parties; unless they live in the same one.

When the parties live in a foreign country, the transfer may be registered in Paris.

•

Of course, the date of registration has to be distinguished from the date of the transfer itself. Both are often mentioned but not always.

•

The notary (name, city) who drafts the transfer contract. Such an information allows to use notarial records to find contracts for this transaction.

•

The buyer is characterized with several information: names, profession, city and address, if the buyer is a company or not.

•

The patent at stake is characterized by its title, its date of granting and its duration.

All these information are quite interesting. But the question remains whether such a source is a relevant indicator about the market for technology. Actually, these transfers were only one part of all the transactions dealing with patents. Some of the agreements were not registered, either the parties did not want to pay the taxes due to the sale, either they did not want to make their deal public. Progressively, licenses and patent contribution to capital were not considered as transfer anymore. In the late 19 th , they progressively disappear from the Bulletin des lois. Only notarial archives or private records can give information about these essential part of patent transfer.

Approaching the market for patents

Pending the implementation of a comprehensive database -a project I am working on with Alexis Grillon -we can focus on two kinds of sources in order to have an overview on patent assignments in the first half in 19 th century France : the INPI database, by being aware of its lacks, and the registrations of assignments provided by the Bulletin des lois. The information provided by the Bulletin must also be considered carefully since it deals first with assignments not with patents: one patent may be sold more than one time and, moreover, an assignment is always registered several months after the agreement itself. However, they provide a good estimate for understanding the volume and intensity of the transactions. While throughout the 19th century, 3 000 patents are issued on average each year, the number of registered assignments is itself one hundred per year. Moreover, the number of registrations and the number of granted patents are not really correlated (Fig. 4 & 5) 23 . If the 1844 reform seems to introduce a strong break in the granting of patents, it does not represent a comparable change for the assignments. Focusing on the period before the 1844 patent law, the gap between granted patents and registered assignments is maybe less important than for the whole 19 th century but the ratio registrations-granted patents remains especially low. This is confirmed by data about the patents themselves from the INPI Database. For this period, about 5% of the granted patents are the subject of an assignment. Although this database is not complete since all the assignments have not been taken into account, the use of confidence intervals suggests that the ratio 'sold patents-granted patents' does not exceed 15% during this period and is probably around 5%. Besides, the ratio seems to decrease from the 1820s with the rise of the patents themselves. What is possible to conclude from this, despite the uncertainty of the source, is the narrowness of patent assignments, which represent only a

Magnitude of assignments

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23. A linear model on the number of registrations and the number of granted patents from 1825 to 1885 has a multiple R-squared = 0.3437, even if p-value = 7.029e-05. However problems of heteroscedasticity have to be fixed. tight part of the patents. If the Revolution did not cause any quantitative rise in patenting, it may neither accelerate significantly the patent assignments. Besides, if the market for patents looks to be more intense at the very late 1820s, this trend does not remain for a long time.

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The problem of patent cost

Going beyond those general data is necessary to have a better understanding of the patent assignments. A Logit model based on the INPI Database suggests that two variables have an effect on the probability of being assigned : the year of deliverance (negative effect) and the initial term of the patent (positive) (see Annex). The first one seems to confirm the relative decrease of assignments but the limitations of this sample must not be forgotten.

For this reason, the analysis is completed by the study of 267 transactions, which were published in 1843 in the Bulletin des lois. This corpus is important enough for detailed statistical studies and it is homogeneous in time. Note, however, that the registrations of certificates of addition and of patent for improvement are excluded so that we can focus on the sale of the patents themselves. A distinction has to be drawn however between the patents, the transfers and the registrations. So the 267 sales recorded in 1843 deal with 203 different patents. In fact, the analysis focuses on five different issues: the transfers, the patents involved in them, the initial holders of these patents, the seller of each patent, and finally their buyers.

A first step is therefore to deal with the patents, which were involved in assignments by comparing them to all granted patents. Of course, the reference granted patents are not the same according to considering the INPI Database or the 1843 registrations. For the former, the parent population consists of all patents issued in the period from 1791 to 1844 since the first patent labelled as "sold" was delivered on 1791 and the last one in 1843. For the later, the parent population consists of all patents issued from 1828 to 1843 since the maximum term of a patent is 15 years. From a statistical point of view, the comparison of these two populations requires a systematic use of the Chi-Squared test and sometimes of confidence interval.

After this methodological clarifications, we can consider the different types of kinds of assigned patents. The 1791 patents laws established three sorts of patents :

-Patents for invention, which protected "every discovery or new invention" 24 ; -Patents for improvement, which protected "every way to bring every kind of production to a new kind of perfection" 25 ; -Patents for importation, which protected "anyone who [would bring] first in France a foreign discovery" 26 .

In practice, hybrid categories were used and some patents were labeled as ones "for invention, improvement and importation" ! Furthermore, the difference between patents for improvement or certificate of addition was far from being clear. It is the reason why in order to facilitate comparisons, only the two first kinds of patents have been considered.

Concerning the data issuing from the INPI database, Chi-Squared test suggests that patent assignment are more related with patents for importation. However, this over-representation is very slight. Actually, this very light effect fits with the result of the logistic regression.

The influence of the kind of industry on the probability is one other interesting aspect. If the logistic regression does not suggest such an effect, the distribution of assigned and granted patents from INPI Database are not totally the same. The fact is that the ceramic industry is a bit overrepresented whereas railways, mining and metallurgical industry and precision instruments industry are underrepresented. However these characteristics are not confirmed in the sample from the Bulletin des lois. Anyway the relationship between assignment and the class industry is all but evident. 25. Patent law of 7th January 1791, article 2. 26. Patent law of 7th January 1791, article 3. The number of patents differs from N=203 because ambiguous patents have been removed from the sample What appears clearly is the over-representation of 10 and 15 years patents in the assigned ones. Of course, this result is not surprising. The longer was the initial term of the patent, the longer the operating time offered to the buyer. Even if there was a possibility of extending the patent term, this procedure was scarce and complex. Moreover, the initial term of a patent is due to its price, a signal of its value. In the absence of a formal examination -there was one but unofficial -the legal, technical and, consequently, financial value of the patents was based on the expertise of intermediaries like technical associations, jury of exhibitions and, at last, on the court decisions. But before being reviewed by such institutions, the patent value depended on the patentee himself. His own investment in the patent cost provides the buyer an objective sign of its value and constitutes an incentive for the transaction.

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Concluding Claims

Despite their limitations, these analyses suggest some conclusions about the patent assignments in the early 19th century France. The 1791 patent laws made the assignability theoretically easier but they did not lead to much frequent assignments in the medium term. As we have seen, the later were limited to less than 10% of patents -probably 5%. Patents for importation were transferred more than the average but they were not significantly over-represented. The distribution of assignments by industry generally fits with that of the patents themselves. The key factor was actually the duration of patents : even if they were much more expensive, long patents might appear as the safest ones to justify transactions : they provided a potentially longer period of use and a probably better value.

In fact, the initial cost of patents is not only a main issue for applying but also for assigning them. This suggests the question whether the link between capitalist and inventor is and what is, ultimately, the quality of the patentee. It also calls to question the impact of the 1844 reform on assignments. By decreasing the effective cost of patents, the 1844 patent reform introduced undeniably strong demand on applications and promoted increasing issuances since preliminary examination was absent whereas the informal one was made much more difficult by this patent 15/18 take-off. In a sense, the 1844 made more uncertain the value of patents.

It is probably one of the reasons why patent assignments did not increase as quick as the patent themselves after 1844. The assignment costs raised while the issuance cost lowered. Of course, the total cost of the patent could remain the same for a given term. But, by postponing this entire payment, the 1844 patent law had the signal of the patentee's confidence in his patent disappeared. The financial risk on patent value was increased and had now to be shared by the patentee and the buyer. Did this inconsistency in the "democratization of invention" reduce the market for patents? Three arguments may qualify this assumption. First such a hypothesis about the influence of the patent cost on assignments is still to be effectively tested. This requires implementing the database on patent assignments in 19th century France. Besides, it seems that actors have found some ways to avoid the new requirements on transfers. While in the first half of the 19th century, licenses or contributions to firm capital were considered as assignments, the legal acception of this notion became much more restrictive in the late century. Consequently licensing was no longer subject to such frequent records. The relationship between the market for French patents and the French market for technology had not the same practical framework. It makes more difficult to track the market for technology but finding new relevant sources is a challenge which historians are used to.

  3. L. HILAIRE-PÉREZ, L'invention technique au siècle desLumières, op. cit. 4. See D. Diderot, « Lettre historique et politique sur le commerce de la librairie », in id., OEuvres complètes, Paris, Garnier frères, 1876, p. 30 ; L. HILAIRE-PÉREZ, « Diderot's views on artists' and inventors' rights: invention, imitation and reputation », The British Journal for the History of Science, 2002, p. 129-150.

Figure 1 :

 1 Figure 1 : Number of Granted Patents, France, 1791-1885 Source : INPI, Guide des sources

Figure 3 :Figure 4 :

 34 Figure 3 : Royal Order announcing granted patents during the 3d quarter of 1824. (Source : Bulletin des lois, 1824)

Fig. 5 :

 5 Fig. 4 : Patent Assignments Registrations (1825-1885) Source : Bulletins des lois

Fig. 6 :

 6 Fig. 6 : Granted Patents and Patent Assignments Registrations(1825-1843) Source : INPI & Bulletin des lois Granted Patents Registered Assignements

  Paris. I had no access to the first catalog but reproductions included in the INPI Guide des sources suggest that both are based on the same model. 21. I thank the INPI for having given me access to the complete database on which further statistics are based. 22. 1BA3668, Hebert and Hussiez patent, which was void in 1835.

	20. MINISTÈRE DE L'INTÉRIEUR, Catalogue des spécifications de tous les principes, moyens et procédés pour lesquels il a été pris des brevets d'invention, de perfectionnement et d'importation depuis le 1er juillet 1791, époque de la mise à exécution des lois des 7 janvier et 25 mai précédens, jusqu'au 1er juillet 1825, Paris, France, A. Boucher : Mme Huzard, 1826 ; Catalogue des brevets d'invention d'importation et de perfectionnement,

Table 1 .Assigned and Granted Patents (1791-1844)

 1

		Source : INPI Database & Guide des sources
	Year of granting	Patents considered as sold by INPI DB	Granted Patents	(1) / (2)	Max CI (0,95)
	1791-1799	5	113	4,22%	22,45%
	1800-1809	17	439	3,87%	13,04%
	1810-1819	63	856	7,36%	13,81%
	1820-1829	191	2081	9,18%	13,27%
	1830-1839	289	4207	6,87%	9,79%
	1840-1843	64	4084	1,57%	4,61%
	N =	629	11780	5,38%	7,10%

Table 2 . Assigned and Granted Patents by sort of patents

 2

			INPI Database
		Assigned Patents	Granted Patents
		n	%	n	%
	Importation	101	16,72%	1519	13,65%
	Invention	503	83,28%	9607	86,35%
	Total	604	100,00%	11126	100,00%
	P-value	0,03
			Bulletin des lois
		Assigned Patents	Granted Patents
		n	%	n	%
	Importation	31	15,66%	1124	13,26%
	Invention	167	84,34%	7352	86,74%
	Total	198	100,00%	8476	100,00%
	P-value	0,32

Table 4 . Assigned and Granted Patents by Initial Term INPI Database Bulletin des lois

 4

		Assigned	Granted	Assigned	Granted
	Term	Patents	Patents	Patents	Patents
	5	26,43%	52,08%	32,67%	51,87%
	10	35,56%	27,21%	28,22%	27,81%
	15	38,01%	20,71%	39,11%	20,32%
	N=	613	11219	202	8672

Patent law of 7th January 1791, article 1.

The key factor is actually the initial term of patents. As said, the 1791 laws allowed to take out a patent for 5, 10 or 15 years. This choice had a double economic dimension: it defined at times the maximum length of the monopoly and also the cost of the patent. 5 year patents costed 300 F, 10 years patents 800F and 15 years ones 1 500F. Long-term patents represented a very significant investment.

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