io Mr. Davy's Lecture on the Decomposition and Composition 
IV. On the Properties and Nature of the Basis of Potash. 
After I had detected the bases of the fixed alkalies, I had 
considerable difficulty to preserve and confine them so as to 
examine their properties, and submit them to experiments ; 
for, like the alkahests imagined by the alchemists, they 
acted more or less upon almost every body to which they 
were exposed. 
The fluid substance amongst all those I have tried, on 
which I find they have least effect, is recently distilled 
naphtha. — In this material, when excluded from the air, they 
remain for many days without considerably changing, and 
their physical properties may be easily examined in the at- 
mosphere when they are covered by a thin film of it. 
The basis of potash at 6c? Fahrenheit, the temperature 
in which I first examined it, appeared, as I have already men- 
tioned, in small globules possessing the metallic lustre, opacity, 
and general appearance of mercury ; so that when a globule 
of mercury was placed near a globule of the peculiar sub- 
stance, it was not possible to detect a difference by the eye. 
At 6 o° Fahrenheit it is however only imperfectly fluids, 
for it does not readily run into a globule when its shape is 
altered ; at 70 ° it becomes more fluid ; and at ioo° its fluidity 
is perfect, so that different globules may be easily made to run 
into one. At 50° Fahrenheit it becomes a soft and malleable 
solid, which has the lustre of polished silver ; and at about the 
freezing point of water it becomes harder and brittle, and when 
broken in fragments, exhibits a crystallized texture, which in 
the microscope seems composed of beautiful facets of a perfect 
whiteness and high metallic splendour. 
