WATERS from ICELAND. in 



would have diffolved it quickly with effervefcence. The quan- 

 tity of this earthy fediment, from either of thefe neutralized 

 waters, was very fmall. From gr. 1 0,000 of Rykum water, I 

 could only collect a quantity, which, after receiving an obfcure 

 red heat, weighed the twentieth part of a grain ; from the fame 

 quantity of the Geyzer water, I got about 38 or 39 hundredths 

 of a grain. 



In one of my experiments with Rykum water, I got this ar- 

 gillaceous earth from it by another procefs. I had a dry ex- 

 tract, obtained by evaporating gr. 20,000 of this water, and which 

 weighed gr. 16^-. Thirty grains of aquafortis were added to 

 it. This aquafortis was made up of equal parts of the ftrongeft 

 nitrous acid and water. The extract was digefted with it fix or 

 eight hours, and then diftilled water being added, the mixture 

 was filtrated in a fmall filtre, to feparate the clear acid liquor 

 from the undifTolved matter. The filtrated acid liquor was then 

 faturated, and a little more than faturated, with a pure aerated 

 alkaline fait, and the faturated mixture was heated to a boiling 

 heat. It became muddy, and depofited a fmall quantity of fe- 

 diment like mucilage, which being collected by nitration, and 

 dried, and heated to an obfcure red heat, weighed juft one tenth 

 part of a grain, and had the qualities above enumerated, which 

 fhewed that it was an argillaceous earth. In another experi- 

 ment, I digefled an extract of Geyzer water with flrong vitriolic 

 acid, and thus got from it a fimilar earth \ but the quantity of 

 it was very little greater than that which I had got by fubfi- 

 dence from the neutralized and boiled part of the fame water, 

 in the experiments above defcribed. 



The greater part, however, of the earthy matter had not yet 

 made its appearance ; I mean the filiceous earth. It flill re- 

 mained in a ftate of perfect difTolution in the neutralized and 

 boiled mixtures above defcribed, fome part of which had ac- 

 tually paffed through filtrating paper ; and I learned, by other 

 trials, that the whole of thefe neutralized mixtures might have 



been 



