not yet sufficiently known. 15^9 



resemblance to nitrate of silver fell to the bottom, and 

 which, by a proper mixture of" concentrated acid^ and the 

 addition of a little water, was again dissolved. 



This precipitation of ciystals before the phosphoric acid 

 was diluted may be easily explained by this circumstance, 

 -that the concentrated acid, which had the appearance of 

 thick syrup, greedily attracted some of the solvent from the 

 nitrate of silver, by which means a part of the nitrate of 

 silver was necessarily obliged to crystallize ; as is the case 

 in all saline solutions when deprived of their aqueous prin- 

 ciples by the addition of other Ijodies, 



As no precipitate was produced by a proper mixture of 

 phosphoric acid with a solution of nitrate of silver, I am of 

 opinion that the assertion of Lavoisier may be confirmed ; 

 namely, that nothing was separated from a mixture of phos- 

 phoric acid and nitrate of silver. 



To obtain more certainty on this subject, T prcpai'cd a 

 siriall quantity of phosphate of silver by precipitating a so- 

 lution of silver with phosphate of soda, one part of which 

 I mixed with nitric acid, and the other with diluted phos- 

 ■phoric acid. In both cases the phosphate of silver was 

 completely dissolved. 



If a decomposition therefore should take place in a mix- 

 " ture of phosphoric acid with a solution of nitrate of silver, 

 ' enough of free acid will stili remain to preveut the prccipi-- 

 tation of the phosphate of silver. 



It however appears from the following experirpcnts thai 

 ; such a decomposition is not probable. 



Two gros of nitrate of silver dissolved in a sufficient 

 quantity of distilled water, were mixed with one gros of 

 concentrated phosphoric acid, and the clear solution wjis 

 subjected to slow distillation over a lamp. 

 ■ The matter which passed over had not the least taste of 

 acid, even when the degree of the heat was increased by 

 enlarging the flame of the lamp. As soon as the formation 

 of small crystals was observed in the retort, I interruptfU 

 the distillati(ni, and left the mixture at rest to cool- 



At the end of several hours a great many crystals of ni- 

 trate of silver had shot up, which when dried gave nearly 

 the same weight again. After repeated s<dution and slow 

 crystallization, all the properties of nitrate of silver were 

 observed. 



The fluid which remained over the crystals in the retort 

 had an exceedingly sour taste, which was perceptibly that 

 of the phosphorjc acid : it Icit on the tongue, liowever, x 



Qietallic 

 I 



