I I 



UNDULATORY FORCES. ELECTRO-METALLURGY. [OOPPM oorviNa. 



through the medium of the bronio and the thin deposit 

 already mentioned, which may be continued to any 

 required thickness in the usual way. In our earlier 

 experiment* with this method, yellow bronze alone waa 

 used, which did not reduce the copper by simple im- 

 mersion ; but even then, medallion* were repeatedly 

 covered with a deposit of copper in from two to fire 

 minute*, which would occupy from twenty to forty-five 

 minute* when prepared by blackload in the usual 

 manner. The addition of white or tin bronse cause* the 

 deposit to spread as rapidly as when the surface is 

 prepared by the phosphorus solution, but without the 

 disadvantage which occurs in using the latter, of milking 

 the deposited metal brittle. The effect of using white 

 bronze alone was not so satisfactory. 



The surface of the copper copy so obtained is bright 

 and clean, and the character of the deposited metal is 

 good, but the surface obtained is hardly so smooth and 

 fine as that obtained with blacklcad; the difference, 

 however, is very slight, and it is sufficiently smooth for 

 all ordinary purposes, and for the object sought, if care 

 be taken to blow off or otherwise remove all superfluous 

 brouze powder before immersing the mould in the vat. 

 We hope that those who may have the opportunity will 

 try it upon a larger scale. 



206. Copying Set-up Type in Copper. The process of 

 clectrotyping has also been gradually encroaching upon 

 that of stereotyping, and has, we are informed, almost 

 superseded that process in America. The plan adopted 

 is similar to that of copying wood-cuts viz., to lay a 

 sheet of softened gutta-percha upon the surface of the 

 page of type, and subject it to increasing pressure until 

 it is cold ; the gutta-percha copy is then removed, and 

 treated as in copying wood engravings. It would bo 

 advisable to try a somewhat softer material for this 

 purpose, such as the mixture of gutta-percha and marine 

 glue, which we have recommended (85). This material 

 takes a sharper and smoother impression than gutta- 

 percha alone, and the deposit spreads over it more 

 rapidly ; and, being softer, it enters more freely and 

 with less pressure between the fine Hues of the letters, 

 and still is not sufficiently soft to penetrate the minute 

 crevices between the body of the types. If a solution of 

 grape-sugar (as used in Drayton's patent process for 

 silvering gloss), aldehyde, or other reducing agent, were 

 substituted for the phosphorus solution, for reducing 

 the silver upon the surface of the mould, it would bo an 

 advantage, as, besides the dangerous character of the 

 phosphorus, it has an offensive odour, and the copper 

 deposited upon surfaces prepared by it, moreover, is 

 invariably brittle. 



The mould may also be prepared for a deposit by 

 blackloading ; it will require a first-rate quality of 

 blocldoad, and prolonged and attentive brushing, but 

 will taen afford a good result. The air-bubbles may bo 

 removed when the mould is in the liquid, by directing a 

 powerful upward current of the liquid against them by 

 means of a vulcanised india-rubber bladder, with a long 

 and curved glass tube having a fine orifice (Fig. 90) at- 

 tached to it; but tho liquid should bo free from 



sediment. 



The advantages of clcc- 

 | trotyping over sterco- 

 ' typing are numerous ; tho 

 metal is harder, takes 

 a sharper impression of 

 the mould, and delivers the ink much more readily than 

 type metal, besides being a cleaner process ; it also takes 

 up less ink, and consequently the printed pages dry 

 more quickly. Both wood-cuts and letter-press have 

 also been copiod in plaster of Paris, and tho deposit of 

 copper formed upon that; but this material is much 

 inferior to gutta-percha for the process. Messrs. Brad- 

 bury and Evans are considered the most successful 

 manipulators in this branch of electro-deposition, and 

 their apparatus tho most perfect of its kind. In this 

 establishment tho temperature of tho room is carefully 

 attended to, and the vessels containing the solutions 

 have gloss coven. Tho result of this careful manipnla- 



Fig. 90. 



tion ha* been, that, in come instance*, successful deposits 

 of large lUuttraied Jfevu engraving* have been formed 

 and taken off in eight hours ; this can only have been 

 effected by the most perfect blacklea.ling, keeping the 

 solution in excellent condition, and working with the 

 maximum of battery power. Gutta-percha and marine 

 glue is well worthy of a trial, and the use of Utuim n 

 with gutta-percha is also a good idea ; tho marine glue 

 would l>o bettor, because it is tougher. 



Iron and stool wire may be coated with an adhesive 

 deposit of copper, by first immersing them, with their 

 surfaces perfectly clean, in the cyanide coppering liquid, 

 and completing the deposit in tho ordinary sulphato 

 solution. Tho coils should be kept separate from each 

 other in the liquid l<y suspending them upon a hi -iy.uiit.-d 

 brass rod, turning it occasionally to causa a uniform 

 deposit. Iron screws and nails may bo treated in a 

 similar manner, except that they should be comaim .1 in 

 a wicker basket, and shook about occasionally to product) 

 a uniform deposit. 



207. Copying Daguerreotype Pictures in Copper. The 

 most interesting and beautiful application of tho de- 

 position of copper, and, at tho same time, one of tho 

 easiest to bo effected, is that of copying Daguerreotype 

 pictures. First solder a wire to tho back of the plato 

 near tho edge ; paint over tho back and edges, and allow 

 it to dry ; hang it in a clean sulphato of copper solution, 

 which is perfectly free from dust or grease on it* surface ; 

 and, in the course of twenty or thirty hours, if about 

 two colls of small Smee's batteries have been used, tho 

 deposit will bo sufficiently thick to be removed; it 

 should then be taken out, well washed, wiped perfectly 

 dry, and a narrow strip be cut off its edges with a strong 

 pair of scissors ; tho two may then be easily separated by 

 inserting the point of a knife, or the end of a thin wedgu 

 of hard wood, between them at the edges. If the pro- 

 cess have been carefully managed, and tho original picture 

 be a strong one, a most beautiful and vivid copy will bo 

 obtained ; and if the picture bo not only a strong one, 

 but has also been well fixed by Fizeau's process, a 

 number of successive copies may be taken from it ; but 

 their intensity, as well as that of the original, appears to 

 diminish in each succeeding trial With a vivid original 

 picture, clear solution, very regular and undisturbed 

 action of the battery, and a fine deposit, we have 

 observed a most strange phenomenon viz., tho picture 

 has not entirely disappeared, even in twenty hours, 

 although tho coating of copper has constantly increased 

 in thickness; the image has penetrated quite through 

 the deposited metal, and appeared upon the back, even 

 upon deposits as thick as an address-card. In some 

 cases the figure was optically positive, and in others 

 negative. 



208. Coating Planter Models, Flowers, and Clay Ftgwrei 

 with Copper. Busts and other similar objects inuy be 

 coated by saturating them with linseed oil, then will 

 blackleading, or treating them with tho phosphorus, 

 silver, and gold solutions, and attaching a number of 

 guiding-wires, connected with all the moot hollow and 

 distant parts. Tho object is then to be immersed in a 

 sulphate of copper solution containing no free acid, and 

 just sufficient copper is to be deposited upon them by 

 tho battery process to protect them, but not to obliterate 

 the fine lines or features. Flowers, fruits, ferns, sea- 

 weed, insects, (be. , may be prepared by tho phosphorus, 

 silver, and gold liquids, and the copper deposited upon 

 them, either by the single cell or battery process, in a 

 neutral sulphate of copper solution. 



209. Coppering Cloth. To copper cloth, first stretch 

 it upon a sheet of copper slightly curved, so that it may 

 be in close contact with tho metal all over ; then varnish 

 the back or hollow side of the copper, and deposit on 

 tho opposite side, by the battery 'process, from a sulphate 

 solution not containing much free acid, until the meshes 

 of the cloth are quite filled with copper, and tho metal 

 and cloth firmly united together ; the deposit may then 

 be removed and well washed : the original sheet of 

 copper should of course bo properly prepared for a non- 

 adhesive deposit. Mr. J. Schottlaondor took out a 



