gos 
eee eee ee 
FE ate AB Rs 
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 firft ef- 
feét of fuch liquor upon the ftained paper will be to change it 
towards afed. ‘This tint of colour, however, being produced 
by the fuperMuous 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.1ooo, 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 morz 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 falt of tartar, and boiled the water again gently until 
it was reduced to gr. 2000. In weighing fuch {mall 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 transferred into the mixture. 
WueEn I now examined the above boiled water, by means of 
the tinétured paper or lien rag, I found it reduced to the exact 
degree of faturation which I defired; that is to fay, it fcarcely 
O 2 produced 
