„_g jvfr. Keiu’s Experiments and Obferv aliens on 
fiances, and of inveftigating the caufe, if I fhould be able, of 
this irregularity and exception to the generally received laws of 
affinity. # . 
2. I digefted a piece of fine filver in pure and pale nitrous 
acid, and while the difl'olution was going on, and before the 
faturation was completed, I poured a portion of the lolution 
upon pieces of clean »nd newly-fcraped iron wire into a wine 
glal's, and obferved a fudden and copious precipitation of filver. 
The precipitate was at firft black, then it afiumed the appear- 
ance of filver, and was five or fix times larger in diameter than 
the piece of iron wire which it enveloped. The aftion of the 
acid on the iron continued fome little time, and then it ceafed; 
the filver re-diffolved, the liquor became clear, and the iron 
remained bright and undifturbed in the folution at the bottom 
of the wine giafs, where it continued during feveral weeks, 
without buffering any change, or effe&ing any precipitation of 
the filver. 
2. When the folution of filver was completely faturated, it 
was no longer affefted by iron, according to Bergman’s 
obfervation. . 
4. Having found that the folution aided on the iron, and 
was thereby precipitated, before it had been iaturated, and not 
afterwards, I was defirous of knowing, whether the faturation 
was the circumftance which prevented the aftion and precipita- 
tion. For this purpofe, I added to a portion of the faturated 
folution fome of the fame nitrous acid, of which a part had 
been employed to diflblve the filver-, and into this mixture, 
non, not being founded on any peculiarity in the nature of iron, feems to fup- 
pofe that the filver is alfo incapable of being precipitated, from fuch folut.ons as 
iron cannot aft upon, by any other metal. But this is not the cale = copper and 
, auc readily precipitate filver from thefe folutions. abounding 
