Electrography. 161 



obtained, have all the sharpness of the original, and may be bronz- 

 ed in the usual way, to any color which may suit the taste of 

 the experimenter.* 



Engraved plates of copper may be copied with equal success 

 by this method, and already this has become an important branch 

 of the engraver's art,f and we hear of large and elaborate plates 

 being thus multiplied to any desired extent. We should suppose 

 that by availing ourselves of this advantage, the great expense 

 of steel plates might be avoided. Such copies may be fur- 

 nished at a price but little exceeding that of ordinary engraver's 

 copper. Mr. Spencer says, that copies of engraved plates may 

 be taken in lead, by pressure as before described, but we should 

 doubt if large plates could be thus treated with success ; and that 

 the first copy ought to be in copper, which when once obtained 

 will answer any number of times. 



But the usefulness of this process would be much abridged 

 were it applicable only to metallic bodies. Such however is not 

 the case. Almost any non-conducting surface may be rendered 

 a conductor by the following ingenious process, proposed by Mr. 

 Spencer. Wash the surface to be metallized with nitrate of silver, 

 by a camel's hair pencil, and then expose this surface thus treated 

 to the vapors of phosphorus dissolved in alcohol or spirits of tur- 

 pentine, which for this purpose should be placed in a capsule, 

 and gently warmed by a spirit lamp, or over a sand-bath. In- 

 stantly the silver is reduced to a phosphuret, and covers the whole 



* A bronzing solution may be made by taking two parts of acetate of copper, and 

 one of muriate of ammonia, and dissolving them in acetic acid (or vinegar;) boil the 

 solution and add water until no longer any white precipitate falls, and only a slight 

 metallic taste remains : filter it, and place the medal to be bronzed in a copper ba- 

 sin ; pour the solution, while boiling, on the object, and keep up the ebullition for 

 some time; examine the medal frequently, and when the desired shade of oxida- 

 tion has been attained, remove it and wash it most carefully in several waters ; oth- 

 erwise a whitish film will subsequently come over it, injuring its appearance. The 

 article to be bronzed must be previously cleaned bright, and be free from all greas- 

 iness. 



\ Beautiful examples of engravings thus obtained, appeared in the Westminster 

 Review, for Septemper last, and side by side with them, impressions from the orig- 

 inal plate. No difference could be perceived on the closest examination. Dr. Chil- 

 ton, of New York, has also obtained equally good results, an example of which 

 was given in the July number of Prof Mapes' American Repertory. We may also 

 add, that we have succeeded in copying a plate, (a head of John Bunyan,) six by 

 nine inches, and that in some future number, we may give some examples, as occa- 

 sion may require. The London and Edinburgh Philosophical Magazine and New- 

 ton's Journal, have also contained examples of this art. 



Vol. XL, No. 1.— Oct.-Dec. 1840. 21 



