“Soda when acted upon in the same manner as potash, exhibited an analogous result; but the decomposition demanded greater intensity of action in the batteries, or the alkali was required to be in much thinner and smaller pieces.”
“The substance produced from potash remained fluid at the temperature of the atmosphere at the time of its production; that from soda, which was fluid in the degree of heat of the alkali during its formation, became solid on cooling, and appeared having the lustre of silver.”
It would seem from his description of its properties that the potassium he obtained was most probably alloyed with sodium derived from impure potash. Potassium is solid up to 143° F.; but, as Davy subsequently found, an alloy of potassium and sodium is fluid at ordinary temperatures.
When the potassium was exposed to air its metallic lustre was immediately destroyed, and it was ultimately wholly reconverted into potash by absorption of oxygen and moisture.
With the substance from soda the appearance and effects were analogous.
When heated in oxygen to a sufficiently high temperature, both substances burnt with a brilliant white flame.
On account of their alterability on exposure to air, Davy had considerable difficulty in preserving and confining them so as to examine the properties of the new substances. As he says, like the alkahests imagined by the alchemists, they acted more or less upon almost every body to which they were exposed.
He eventually found that they might be preserved in naphtha.
The “basis” of potash at 50° F. was a soft and malleable solid with the lustre of polished silver.
“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.”
It may be converted into vapour at a temperature approaching a red-heat, and may be distilled unchanged; it is a perfect conductor of electricity and an excellent conductor of heat. Its most marked difference from the common run of metals was its extraordinarily low specific gravity. Davy endeavoured to gain an approximation to its relative weight by comparing the weight of a globule with that of an equal-sized globule of mercury.