98 Sate AN ABC SL Se ge 
both of them. The sth trial fhewed that the alkaline matter 
was not calcareous earth, but alkaline falt; and the Oth, that 
this alkaline falt was not the volatile, but one of the fixed al- 
kalis. The 1ft trial fhewed, that this unfaturated fixed alkali 
was not combined with air, or that if any was combined with 
it, the quantity was fo fmall as to be f{carcely perceptible. 
None of thefe trials gave any indication of the earthy matter 
contained in thefe waters; and as my principal obje@ was to 
inveftigate the nature of their petrifying power, I now began 
with the following experiment : 
Evaporation of the Water. 
I EVAPORATED 10,000 grains weight of each of thefe waters 
to drynefs with a gentle heat, in feparate glaffes. The dry ex- 
tract of the water of Rykum weighed gr. 8.25, and that of 
Geyzer, gr. 10. 
THE evaporation was performed in cylindrical glafs veffels, 
about 3 inches wide and 7+ deep, which received heat from the 
fteam of boiling water, not directly, but through the interven- 
tion of white-iron cafes, which fitted the glaffles, and in which 
they hung. I have often ufed this apparatus in examining and 
comparing different waters ; and the advantages of it are, that 
-the greater part of the fixed matter is collected on a fmall fur- 
face; that the glafles are fo moderately heated, that they bear 
water to be added, during the evaporation, without danger of 
breaking ; and, laftly, when the whole water is evaporated, the 
fixed matter, while it is thoroughly dried, by leaving it expofed 
fome hours to the heat, never becomes fo hot as to fuffer the lof 
of any part of the acid of the faline compounds which it may 
contain, and when it is dry, the quantity of it is accurately de- 
termined, by weighing it in the glafs, the weight of which can 
be 
