54i -MV. Davy’s Experiments on 
gas, the pure alkalies were formed in a state of extreme dry- 
ness ; and that 100 parts of potassium, absorb about 18 parts' 
of oxygene, and 100 parts of soda about 34 parts. Though in 
the experiments from which these deductions were made, 
very small quantities only of the materials were employed, 
yet still from frequent repetitions of the process, I hoped 
that they would approach to accuracy ; and I am happy to 
find that this is the case ; for the results differ very little in 
some experiments which I have made, upon considerable 
portions of potassium and sodium, procured by chemical 
decomposition. 
When potassium is burnt in trays of platina, in oxygene 
gas that has been dried by ignited potash, the absorption of 
oxygene is about ~~ of a cubical inch for every grain of 
the metal consumed ; and when sodium is burnt in a si- 
milar manner, about a cubical inch is taken up for every 
grain.* The alkalies so formed, are only imperfectly fusible 
at a red heat; and do not, like the easily fusible alkalies, give 
indications of the presence of moisture.. 
M. D’Arcet has shewn by some very well conducted en- 
quiries, that potash and soda/f in their common state,, contain 
a considerable proportion of water ; and M. Berthollet con- 
cludes, that 100 parts of potash, that have been kept for some 
time in fusion, contain 13.89 parts of water, which is lost 
when the alkali enters into combination with muriatic acid ; 
and the same sagacious observer, from some very minute 
experiments, infers, that muriate of potash, which has been 
* The quantities of gas given out by the operation of' water; are in a similar ratios. 
See page 43 of the last Bakerian lecture, and page 26 of this paper. 
f Annales de Chinaie. Nov. 1.808, page 175. 
