88 Mr. Davy’s Lecture on some new analytical Researches 
out was similar to that produced by the combustion of liver 
of sulphur. 
The water which had acted upon a portion of it was exa- 
mined ; a number of chocolate coloured particles floated in it. 
When the solid matter was separated by the filter, the fluid 
was found to contain fluate of potash, and potash. The solid 
residuum was heated in a small glass retort in oxygene gas ; 
it burnt before it had attained a red heat, and became white. 
In this process, oxygene was absorbed, and acid matter pro- 
duced. The remainder possessed the properties of the sub- 
stance formed from fluoric acid gas holding siliceous earth in 
solution, by the action of water. 
In experiments made upon the combustion of quantities of 
potassium equal to from six to eleven grains, the portion of 
matter separable from the water has amounted to a very small 
part of a grain only, and operating upon so minute a scale, I 
have not been able to gain fully decided evidence, that the in- 
flammable part of it is the pure basis of the fluoric acid ; but 
with respect to the decomposition of this body by potassium, 
and the existence of its basis at least combined with a smaller 
proportion of oxygene in the solid product generated, and the 
regeneration of the acid by the ignition of this product in 
oxygene gas, it is scarcely possible to entertain a doubt. 
The decomposition of the fluoric acid by potassium, seems 
analogous to that of the acids of sulphur and phosphorus. In 
neither of these cases are the pure bases, or even the bases in 
their common form evolved ; but new compounds result, and 
in one case sulphurets, and sulphites, and in the other phos- 
phurets, and phosphites of potash, are generated. 
As silex was always obtained during the combustion of the 
