240 



UNDULATORY FORCES.-ELECTRO-METALLURGY. [jouBKKr'g 



November 26th, 1852. M. Joubcrt describes hii process 

 M follows : 



" The liut century produced many engravers of groat 

 merit ; and, in thii country, foremost amongst thorn are 

 Hogarth, Sir Robert Strange, and James Heath. The 

 excellence of their works gave rise to such a demand for 

 print impressions of engravings, that some forty yean 

 ago, when it was found that a copper plate could not 

 yield a sufficient number of impressions for the demand, 

 steel plates were introduced, for small plates only at first, 

 and several editions of books were published containing 

 plates most elaborately engraved on steel 



" Subsequently, when means were found to obtain a 

 large surface of steel of pure quality, this metal was 

 adopted for the style of engraving known as mezzotinto, 

 which is now practised on steel plates, tho result being a 

 much larger number of impressions obtainable as com- 

 pared with the old copper plates ; but historical or lino 

 engraving, for important subjects, was still entirely prac- 

 tised on copper, when the discovery of tho art of electro- 

 typing took place, about the year 1838. 



"Several lino engravings on copper wero then multi- 

 plied by this process ; tho result, however, was only 

 attended with partial success, in consequence of the soft 

 quality of the copper so deposited, which will yield but a 

 very limited number of good impressions, and soon wears 

 away : this caused the process to bo almost abandoned 

 for artistic engraving ; but for commercial purposes it is 

 still practised extensively, and has been often successfully 

 applied in cases where a largo number of impressions is 

 not required. 



" Under the circumstances which I have described, it 

 had become a desideratum to harden, if possible, the sur- 

 face of a copper plate, and to protect it from wear while 

 printing ; but it is only lately that this important object 

 has been attained. 



" In March last, my friend M. Jacquin, of Paris, took 

 out a patent in this country for a method of coating- 

 plates with iron, which hod already been successfully 

 applied in France, and of which the merit is duo to my 

 friend, II. Henri Cornier, of Paris. 



" I have myself had the advantage of co-operating with 

 M. Gamier in the development of the invention, the 

 principles of which I shall now proceed to describe. 



"If the two wires of a galvanic battery be plunged 

 separately into a solution of iron, having ammonia for its 

 basis, the wire of the positive pole is immediately acted 

 upon, while that of the negative pole receives a deposit 

 of the metal of the solution. This is tho principle of the 

 process which wo have named 'ocierage.' 



" The operation takes place in this way : By placing 

 at the positive pole a plate or sheet of iron, and immers- 

 ing it in a proper iron solution, the metal will be dis- 

 solved under the action of tho battery, and will form 

 hydrochlorate of iron, which, being combined with tho 

 hydrochlorate of ammonia of tho solution, will become a 

 bichloride of ammonia and iron : if a copper plate be 

 placed at the opposite pole, and likewise immersed, the 

 solution being properly saturated, a deposit of iron, bright 

 and perfectly smooth, is thrown upon tho copper plate, 

 from this principle : 



" Water being composed of hydrogen and oxygen ; 



" Sal-ammoniac being composed of 



" 1st. Hydrochloric acid containing chlorine and hydro- 

 gen ; 



"2nd. Ammonia, containing hydrogen, nitrogen, and 

 oxygen ; 



" The water is decomposed under tho galvanic action, 

 and tho oxygen fixes itself on the iron plate, forming an 

 oxide of iron ; the hydrochloric acid of tho solution act- 

 ing upon this oxide, forms a hydrochlorato of iron, whilst 

 the hydrogen precipitates itself upon the plate of the 

 negative pole, and, unable to combine with it, conies up 

 to the surface of the solution in bubbles. 



"My invention has for its object certain means of 

 preparing printing-surfaces, whether for intaglio or sur- 

 face printing, so as to give them tho property of yielding 

 a considerably greater number of impressions than they 

 are capable of doing in their ordinary or natural state. 



And the invention consists in covering the printing-sur- 

 faces, whether intaglio or relief, and whether of copper 

 or other soft metal, with a very thin and uniform coating 

 of iron, by means of electro-metallurgical processes. 

 The invention is applicable whether the device to bo 

 printed from be produced by engraving by hand, or by 

 machinery, or by chemical means, and whether the sur- 

 face printed from bo the original or an electrotype 

 surface produced therefrom. I would remark, that I am 

 aware that it has been before proposed to coat type and 

 stereotypes with a coating of copper, to enable tlu-ir 

 surfaces to print a larger number of impressions than 

 they otherwise would do ; I therefore lay no claim to tho 

 general application of a coating of harder metal on to 

 tho surface of a softer one, but my claim to invention is 

 confined to tho application of a coating of iron by ii 

 of electricity on to copper and other metallic printing 

 surfaces. 



"In carrying out the invention, tho solutions of iron 

 employed may be varied ; and such is tho cose in respect 

 to the arrangement of tho galvanic battery, or other 

 source of electric currents used. I do not, thenf. >rf, 

 limit the invention to tho means hereinafter dnonbed, 

 but I believe they will bo found to bo tho best fur tho 

 purpose. 



" I would further remark, that it is important that a 

 ferric solution should bo employed which will not dis- 

 solve or corrode tho plato intended to bo coated ; for if it 

 be attempted to use such a solution, though the iron 

 will bo precipitated, it will not only bo in a non-coheront 

 state, but the engraved surface itself will be liable to bo 

 attacked and injured. It may also bo remarked, that tho 

 coating of iron admits of being removed from a printing- 

 surface of copper without injury to tho original plate ; 

 henco tho original plato may, after being coated and 

 used for some time, have the worn coating removed, and 

 then be recovered with an iron coating as often as may 

 be required ; and if care be taken to remove the coating 

 of iron before it has been entirely worn away, the en- 

 graved copper or other plate may be made to print a 

 vast number of impressions, ami yet remain in tho 

 original state it was in when it left the hands of the en- 

 graver, or was otherwise first produced : tho only limit 

 appears to bo in tho gradual change which takes place in 

 the body of the printing-surface, by the compression to 

 which it is subjected in the process of printing. Hereto- 

 fore, in respect to plates engraved in intaglio, if of steel, 

 they each yield, on. the average, about 3,000 impressions 

 without retouching : if of copper, they each yield, on 

 an average, not more than 800 without retouching ; 

 whilst electro casts of copper, obtained from the originals, 

 will not, on an average, each yield even 200 im- 

 pressions without retouching : in fact, such printing- 

 surfaces are so easily worn, that, after the first 100 

 or 150 impressions, there is a considerable deterioration 

 in the quality of the work produced. Therefore, for tho 

 supply of the number of impressions often required by 

 art associations and others, it has been found necessary 

 to multiply tho electro casts very considerably. In 

 such cases tho invention is applicable with considerable 

 advantage ; for I find that an electro plate, 40 X 22 inches, 

 covered or coated with iron, has yielded 2,000 impres- 

 sions without its being necessary to remove ami i 

 tho iron coating, there being no perceptible difference 

 between the first and lost impression ; tho work on tho 

 plate appearing not to have suffered in the slightest 

 degree. Hence, in future, by the application of the in- 

 vention, it will only be necessary to multiply electro 

 casts to such an extent as may be necessary to ensure 

 tho production of prints or impressions with tho requisite 

 speed, on paper, calico, or other fabrics. At tho sanio 

 time, an original engraving on copper would become, 

 when treated according to the invention, more lasting 

 than if engraved on steel. Although original surfaces 

 engraved in relief, and also electro and other casts taken 

 from them, yield a considerably greater number of im- 

 pressions than those I have mentioned as obtained from 

 plates engraved in intaglio to which the invention has 

 not been applied nevertheless the invention is applicable, 



