*4 Afr. Davy’s Experiments on the 
the potassium had been covered with a considerable crust of 
hydrat of potash. The upper part of the retort and its neck 
contained a white sublimate of hydrat, which had risen in 
combustion, and which was perfectly opaque. As soon as 
the gas was admitted, it instantly became transparent from the 
evolution of water ; and on heating the glass in contact with 
the sublimate, its opacity was restored, and water driven off'. 
In various cases in which I heated dry potash, or mixtures 
of potash and the peroxide, in oxy muriatic gas, there was no 
separation of moisture, except when the gas contained aqueous 
vapour ; and the oxygene evolved in the process, when the 
heat was strongly raised, exactly corresponded to that ab- 
sorbed by the potassium. 
When muriatic acid gas was introduced to potash formed 
from the combustion of potassium, water was instantly 
formed, and oxymuriate of potassium.* I have made no ac- 
curate experiment on the proportions of muriatic acid gas de- 
composed by potash, but I made a very minute investigation, 
of the nature of the mutual decomposition of this substance, 
and hydrat of potash. 
Ten grains of hydrat of potash were heated to redness in a 
tray of piatina, which was carefully weighed ; it was intro- 
duced into a retort which was exhausted of air, and the retort 
was filled with muriatic acid gas. The hydrat of potash was 
heated by a spirit lamp ; water instantly separated in great 
abundance, and muriate of potash formed. A strong heat 
was applied till the process was completed, when the tray was 
taken out and weighed ; it had gained 2-fJ- grains. A minute 
quantity of liquid muriatic acid was added to the muriate, to 
* i. e. Muriate of potash. 
