INDUSTRIAL PROGRESS DURING THE YEAR 1872. Jxiii 



more applicable in certain connections. Gun-cotton, how- 

 ever, still continues to hold its own as an explosive; and the 

 recent discovery that a combination with 20 per cent, of its 

 weight of water does not materially affect its explosive pow- 

 er when set off with a fulminate, while it protects it against 

 accidental ignition, will probably give to it the preference, 

 in manv cases, over its rivals. 



Our limitations of space will not permit us to go into detail 

 in reference to Technology, although the chemical branch of 

 the subject has been referred to under the head'of Chemistry. 



For information in this department, the special journals 

 in America, more particularly The Scientific American and 

 The American Artisan, may be consulted with great profit. 

 A few points, however, may be touched upon as being of gen- 

 eral interest. 



In the department of the liberal arts, progress continues 

 to be made in the application of photography for purposes 

 of illustration, numerous new processes having been an- 

 nounced, and improvements in the older ones. At the pres- 

 ent time, the favorite methods of auto-type printing are those 

 of Albert, as modified by Edwards of London, and that of 

 Mr. Woodbury. Both of these have lately been applied suc- 

 cessfully in illustrating natural history objects, and in the 

 same work, that by Mr. Alexander Agassiz upon the Echini. 

 The extreme volatility of metallic mercury as ascertained by 

 Merget, has already been used by him in the production of 

 pictures, and seems likely to receive an extended application 

 hereafter. 



The usual number of new dyes has been introduced during 

 the year, many of them anilines, and others of a different 

 composition. 



The subject of pyro-plating, or the coating of one metal by 

 another by first depositing a layer of the latter by electricity 

 or otherwise, and then burning it in by the application of 

 heat, has received much attention during the year, and has 

 been applied very successfully to the plating of knives and 

 other objects exposed to a great amount of friction. 



Economy in the manufacture of paper has been advanced 

 by improved methods of converting wood into pulp, this sup- 

 plying a basis for printing papers especially, at a much less 

 cost than those from linen or even cotton. 



