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making this experiment I found that the 

 fleeces, on increafing the quantity of water, 

 became lefs fenfible in the infufion of folu- 

 tion of filver ; and, adding ftill more water, 

 a flight turbidnefs was at length produced 

 without fleeces or ftreaks : whence it ap- 

 peared evident that the turbidnefs in queftion 

 was the effed: of a very flight portion of 

 the muriatic acid, which had pafled from 

 the volcanic glafles into the water. 



I took twelve ounces of each of the 

 glafles, the fpotted and the black, reduced 

 them to powder, and boiled them feparately 

 in diftilled water four fucceflive times, fifteen 

 hours each time ; then ftraining ofl*the water, 

 I evaporated it to drynefs, and found at the 

 bottom of the vcflel a refidue of fine glafs- 

 powder. On this I poured a little dillilled 

 water, and tried one part of this water with 

 the tincture of turnfole, and the other with 

 nitrate of fflver. In the former arofe a thin 

 reddifli fume, and in the latter a flight tur- 

 bidnefs, not without a few white fleeces. 



I took 



