■Reiluction of 

 tlie muriate. 



C)3 SILVER COITfS. 



new portion substituted. This was repeated till the water 

 came off pj^rfectlj' pure. The precipitate v\"as then washed 

 out of the vessel into a glass or porcelain capsule, and the 

 water being drained, it was dried for two hours upon a sand 

 bath, heated nearly to the temperature of 400" the vessel was 

 then caretully weighed, first with the muriate in it, and then 

 after that substance had been removed, the difference gave 

 the exact weight of muriate of silver dried in a heat rather 

 under 400®. 



In the eariler analyses, the &ilver was reduced from this mu- 

 riate by fusing it with common potash. But this method was 

 found liable to some. uncertainty. If the heat be suddenly 

 raised, a portion of the muriate of silver is apt to be volatil- 

 ized, even though covered with potash ; and even when we suc- 

 ceed in preventing this, it is but seldom that the whole of the 

 silver is united ir>a single mass. Small globules very frequent- 

 ly .sink into the crucible, and can with difficulty be collected. 

 For these reasons, I found it more convenient, as well as pre- 

 cise, to estimate the weight of the silver from the dried 

 muriate. 

 ?ffaiitlari1 ex- A hundred grains of pure silver, reduced from the muriate, 

 » educe'the'sil- ^'^'^^^ dissolved in nitric acid, and evaporated gently till th© 

 contained whole was brought to a state not unlike that of calcined borax. 

 The weight was 157.18 grains. Vt'hen the heat was conti- 

 nued, fumes of nitrous acid soon filled the. retort, and the 

 silver was reduced, appearing in the state of fine crystalline 

 flakes. A hundred grains of pure silver were dissolved in 

 nitric acid, evaporated to dryness, redissolvcd in water, and 

 precipitated by muriate of soda ; the precipitate, being well 

 washed, was placed for two hours on a sand bath, heated nearly 

 to 400°. It was allowed to cool, and then weighed. It was 

 again placed on the sand bath for two hours more, but the 

 weight was not altered. It was allowed to stand for two 

 days, exposed to the open air, in a dry room, but no alteration 

 in its weight took pl.'ice : the weight was 132.35 gr. I then 

 put the glass capsule, containing the muriate, into a crucible, 

 surrounded it wjth sand, and brought the muriate to fusion : 

 it now weighed only 128.67 gr. From this experiment it 

 follows, that nUiriate of silver, dried at a heat of U' arly 400°, 

 contains 0.7564 of silver; and when melted, 0776"4. A 

 repetition of the experiment gave very nearly the same re- 

 sult. • 



ia the mifi-iate. 



