98 An AN ALT SIS of 



both of them. The 5th trial mewed that the alkaline matter 

 was not calcareous earth, but alkaline fait ; and the Oth, that 

 this alkaline fait was not the volatile, but one of the fixed al- 

 kalis. The 1 ft trial (hewed, 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 fcarcely perceptible. 



None of thefe trials gave any indication of the earthy matter 

 contained in thefe waters ; and as my principal object was to 

 invefrigate the nature of their petrifying power, I now began 

 with the following experiment : 



Evaporation of the Water. 



I evaporated 1 0,000 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. ic. 



The evaporation was performed in cylindrical glafs veffels, 

 about 3 inches wide and y± deep, which received heat from the 

 fleam of boiling water, not directly, but through the interven- 

 tion of white-iron cafes, which fitted the glaffes, 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 glaffes 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 lofs 

 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 



