go Mr. Davy’s Lecture on the Decomposition and Composition 
indicated a temperature of 56° Fahrenheit, and the barometer 
an atmospheric pressure equal to 2 g.6 inches. 
Now this quantity of hydrogene* would require for its com- 
bustion a volume of oxygene gas about equal to that occupied 
by 154.9 grains of mercury, which gives the weight of oxy- 
gene required to saturate the .08 grains of the basis of potash 
at the mean temperature and pressure nearly .01 5 i grains. 
And .08 + .0151= .0951 : .08 : : 100 : 84.1 nearly. 
And according to these indications 100 parts of potash con- 
sist of about 84 basis and 16 oxygene. 
In an experiment on the decomposition of water by the 
basis of soda, the mercury in the barometer standing at 
30.4 inches, and in the thermometer at 52 0 Fahrenheit, the 
volume of hydrogene gas evolved by the action of .054 
grains of basis equalled that of 32 6 grains of quicksilver. 
Now this at the mean temperature and pressure would 
require for its conversion into water, .0172 of oxygene, and 
:0 54+- 01 7 2 =-°7 12 : -054: : 100 * 7^ nearly; and according 
to these indications, 100 parts of soda consist of nearly 7 6 
basis, and 24 oxygene. 
In another experiment made with very great care, .052 of 
the basis of soda were used ; the mercury in the barometer 
was at 29.9 inches, and that in the thermometer at 58° Fah- 
renheit. The volume of hydrogene evolved was equal to 
that of 302 grains of mercury; which would demand for its 
saturation by combustion, at the mean temperature and 
pressure .01549 grains of oxygene; and 100 parts of soda, 
according to this proportion, would consist nearly of 77 basis, 
and 23 oxygene. 
* Researches Cbent. and Phil, page 287. 
