WATERS from ICELAND. 107 



and that, though a liquor contain a fmall quantity of alkali, if 

 , this be faturated and fuperfaturated with fixed air, the firlt ef- 

 fect of fuch liquor upon the flamed paper will be to change it 

 towards a fed. This tint of colour, however, being produced 

 by the fuperfluous aerial acid, is made to difappear, by drying 

 the bit of cambric. The colour of it, while drying, will 

 quickly change from the red to purple, and from that to blue, 

 in confequence of the evaporation of the fuperfaturating air. 

 Being apprifed of this particular, I firft made fome preparatory 

 experiments, with gr. 1000, and alfo with gr. 10,000 of the 

 Geyzer water, and afterwards a more fatisfactory one with 

 gr. 10,000 of the fame, in the following manner : 



To gr. 10,000 of the Geyzer water, I added gr. 400, accu- 

 rately weighed, of the largely diluted vitriolic acid, and began 

 foon after to evaporate the water, by boiling it gently in a thin 

 bottomed glafs. The above quantity of acid I knew to be 

 confiderably mors than what was fufficient for faturating the 

 alkali. 



„ The water was boiled until it was reduced to a quantity 

 little exceeding gr. 3000. I then added gr. 84.5 of the dilute 

 folution of fait of tartar, and boiled the water again gently until 

 it was reduced to gr. 2000. In weighing fuch fmall quantities 

 of acid or alkaline liquors as were added to the water in thefe 

 experiments, it is eafy to adjuft the weight with the greateft 

 precifion, by dipping the end of a flender glafs rod, or of a 

 pointed flip of paper, into the fluid. By thefe means, we can 

 take up a quantity of it, as fmall as we pleafe; and this me- 

 thod I likewife ufed, when I meant to add thefe fluids gra- 

 dually, and by very fmall quantities at a time, to any mix- 

 ture. The end of a flender glafs rod was dipped into them, and 

 'afterwards iransferred into the mixture. 



When I now examined the above boiled water, by means of 

 the tinctured paper or linen rag, I found it reduced to the exact 

 degree of faturation which I defired ; that is to fay, it fcarcely 



O 2 produced 



