﻿49^ SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 



for several of the government Departments, but when the cheaper 

 photo-engraving processes were perfected, they supplanted wood 

 engraving, and this method dropped out of use. 



Now that there has been a revival of wood engraving I have 

 thought that the publication of this method might benefit those in- 

 terested in such work. I will begin with the silver bath which 

 should be prepared in the following manner: 



Water 100 c.c. 



Nitrate of silver 8 grams. 



Iodide of potash 2 decigrams. 



Add oxide of silver, stirring until an excess remains undissolved. 

 then set in the sun for five or six weeks, when it should be taken in 

 and decanted. This is called an alkaline silver bath and must not 

 be acidified. 



Collodion 



Alcohol 95 per cent 60 c.c. 



Sulphuric ether 40 c.c. 



Ammonium iodide 7 decigrams. 



Ammonium bromide 2 decigrams. 



Pyroxlin 1.5 grams. 



Developer 



Water 100 c.c. 



Ferrous sulphate 2 grams. 



Glacial acetic acid 1,3 c.c. 



Toning Bath 

 This should have an acid reaction. 



Water 100 c.c. 



Gold chloride pure 2 decigrams. 



Film Solvent 



Sulphuric ether 100 c.c. 



Alcohol 50 c.c. 



( ibtain plate glass without scratches and immerse in nitric acid, 

 then wash and set it in a rack to dry. Take a negative of the object 

 to be engraved, place it in the window as if to make a transparency 

 except that the glass side should face the lens, coat the glass with the 

 collodion and immerse in the silver bath just long enough to sensi- 

 tize it. Expose in the camera as for an ordinary transparency, 

 develop until all detail appears by reflected light, hut keep the whites 

 perfectly clear, wash thoroughly and fix in 



Water 1 liter. 



Cyanide of potash 10 grams. 



