of the fixed Alkalies. 27 
not possible to raise it to the point required for the process,, 
without softening the glass. 
In all cases the globules of the alkaline bases were carefully 
freed from naphtha before they were introduced ; of course 
a slight crust of alkali was formed before the combustion, but 
this could not materially affect the result ; and when such a 
precaution was not used, an explosion generally took place 
from the vaporization and decomposition of the film of naphtha 
surrounding the globule. 
After the combustion, the absorption of gas was ascertained, 
by opening the lower point of the tube under water or mercury. 
In some cases the purity of the residual air was ascertained, 
in others the alkali formed in the tray was weighed. 
From several experiments on the synthesis of potash by 
combustion, I shall select two, which were made with every 
possible attention to accuracy, and under favourable circum- 
stances, for a mean result. 
In the first experiment 0.12 grains of the basis were 
employed. The combustion was made upon platina, and was 
rapid and complete ; and the basis appeared to be perfectly 
saturated, as no disengagement of hydrogene took place when 
the platina tray was thrown into water. The oxygene gas 
absorbed equalled in volume 190 grain measures of quick- 
silver ; barometer being at 29.6 inches, thermometer 62° Fah- 
renheit ; and this reduced to a temperature of 6o° Fahren- 
heit, and under a pressure equal to that indicated by 30 
inches,* would become 186.67 measures, the weight of which 
• In the correction for temperature, the estimations of Dalton and Gay Lussac 
are taken, which make gasses expand about T f 5 of the primitive volume for every 
degree of Fahrenheit. 
