Progress of Foreign Science. 397 



Siibuitrate of iron, prepared by a powerful evaporation, and 

 dried in a glass tube, til! it was on the verge of decomposition, 

 consisted of — 



Tritoxide of iron . 1.543 ... 4 atoms . . . 81.26 



Nitric acid .... 0.267 ... 1 . . . 14.06 



Water 0.088 ... 2 . . . 4.68 



Tl98 100.00 



Subnitrate of bismuth. 2.827 parts of the salt, precipitated 

 by water, and dried with precaution on the fire, were found to 

 consist of — 



Oxide ... 2 atoms . . . 2.405 



Acid ... 1 . . . 0.413 



"2^818 



5.348 of the same subnitrate, dried in vacuo, by means of 

 sulphuric acid, left 4.353 of oxide after calcination ; they con- 

 sisted of — 



Oxide .... 4.353 ... 2 atoms . . . 81.37 



Acid .... 0.747 ... 1 . . . 13.97 



Water .... 0.248 ... 2 . . . 4.66 



Too.oo 



Sub-protonitrate of mercury, precipitated by water. Its 

 black oxide was separated by potash in excess, collected on a 

 filter and weighed. 8.979 parts yielded 7.947 of oxide. 



Oxide of mercury . 7.947 ... 2 atoms . . . 88.60 

 Acid 1.022 ... 1 . . . 11.40 



Sub-deutonitrate of mercury, precipitated hy water, gave a 

 compound of — 



Oxide .... 3.901 ... 2 atoms . . . 88.97 

 Acid .... 0.484 ... 1 . . . 11.03 



' Ts'ss Too^oo 



When it is precipitated, by alkali not in excess, this sub-deuto- 

 nitrate cannot be washed, because water decomposes it in- 

 stantly and completely ; and even the preceding sub-deuto- 

 nitrate is destroyed by boiling water, which carries off the whole 

 of the acid, with a little oxide. It becomes, therefore, neces- 

 sary to filter the sub-deutonitrate separated by the potash, 

 to compress it between papers, and dry it iii vacuo. It was then 

 of a fine yellow colour, and did not decompose in the air. 

 Two analyses gave more acid than was requisite for the consti- 

 tution of two atoms of oxide and one of acid. But as it still 

 retained much neutral nitrate, it is almost certain, says M. 

 Grouvelle, that its composition was as follows : — 



Vol. Xlir. 2E 



