380 SALTS 



1 atom phosphoric acid 3-5 



1 atom peroxide of copper 5 



1 atom water 1-125 



9*625 



His water exceeded an atom by one third ; but 

 as the salt was in the state of powder, this sur- 

 plus was no doubt mechanical. 



5. Arseniate of copper. This salt has been 

 met with in considerable quantity in Huel Gar- 

 land copper mine, in the parish of Gwennap, 

 Cornwall. It was analyzed by Chenevix, who 

 found it to consist of four different varieties, dis- 

 tinguished also by the shape of the crystals and 

 the colour. He formed, likewise, an arseniate of 

 copper differing from any of these four varieties, 

 by mixing solutions of arseniate of ammonia and 

 nitrate of copper together, filtrating the mixture, 

 and adding alcohol to the liquid which passed 

 through the filter : rhomboidal crystals of a blue 

 colour gradually precipitated. 



These analyses were made at a time when the 

 data were not quite so accurate as at present, 

 and no modern chemist has had it in his power 

 to repeat them. But I think it probable, from 

 Mr. Chenevix's analyses, that these five kinds of 

 arseniates were composed as follows : 



(1.) Artificial arseniate, 



