12 Mr. Davy's Lecture on the Decomposition and Composition 
known. In its solid form it is a little heavier, but even in 
this state when cooled to 40° Fahrenheit, it swims in the 
double distilled naphtha. 
The chemical relations of the basis of potash are still more 
extraordinary than its physical ones. 
I have already mentioned its alkalization and combustion 
in oxygene gas. — It combines with oxygene slowly and with- 
out flame at all temperatures that I have tried below that of 
its vaporization. — But at this temperature combustion takes 
place, and the light is of a brilliant whiteness and the heat 
intense. When heated slowly in a quantity of oxygene gas not 
sufficient for its complete conversion into potash, and at a 
temperature inadequate to its inflammation, 400° Fahrenheit, 
for instance, its tint changes to that of a red brown, and when 
the heat is withdrawn, all the oxygene is found to be absorbed, 
and a solid is formed of a greyish colour, which partly con- 
sists of potash and partly of the basis of potash in a lower 
degree of oxygenation, — and which becomes potash by being 
exposed to water, or by being again heated in fresh quantities 
of air. 
The substance consisting of the basis of potash combined 
with an under proportion of oxygene, may likewise be formed 
by fusing dry potash and its basis together under proper cir- 
cumstances. — The basis rapidly loses its metallic splendour ; 
the two substances unite into a compound, of a red brown 
colour when fluid, and of a dark grey hue when solid ; and 
this compound soon absorbs its full proportion of oxy- 
gene when exposed to the air, and is wholly converted into 
potash. 
And the same body is often formed in the analytical 
