558 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



plate is then taken from the frame in the dark room and 

 washed with water for five or ten minutes, till the relief is 

 fully developed, after which it is dried with filtered paper 

 and coated with glycerine by means of a camel's-hair pencil, 

 and the excess of liquid is removed with filter-paper. From 

 this plate a cast is made in plaster of Paris of the consist- 

 ency of oil, and from the plaster cast a metal one may be 

 taken. 21 A, Sept., 1874, 930. 



PHOSPHOE-BRONZE. 



M. Delatot, in an article ujdoii " phosphor-bronze," states 

 that it is not an alloy, but a true chemical combination of 

 copper with phosphorus, or a phosphide of copper in definite 

 proportions. The union of the two may be through the 

 cold or the hot process, the cold sufficing for certain appli- 

 cations, being preferable indeed to combinations produced 

 by heat. By the hot process the introduction of simple 

 bodies other than the metals or metalloids is prevented. 

 The copper used in the process must be commercially pure. 

 Of the three kinds of phosphorus the operator may take his 

 choice : the ordinary, the amorphous, and the earthy biphos- 

 phates. The amorphous is the most expensive, and is also 

 the best. According to Delatot, the percentage of phos- 

 phorus varies from 2 to 4, between which there may be an 

 infinity of degrees, although for industrial purposes five va- 

 rieties meet all the requirements. These are formed with 2 

 per cent, of phosphorus, 2 -J- per cent., 3, 3 J, and 4 per cent. 

 Above 4 phosphor-bronze is useless, but between 3 and 4 

 per cent, the material is claimed to be superior to any other 

 metal or alloy. The price of phosphor-bronze, unworked, 

 should not exceed that of copper plus 10 per cent. 18 ./l, 

 April 9, 1875, 97. 



