MEMOIR OF THE LATE DR. HENRY. 113 
of only one-fifth of an inch in diameter. After 
admitting water to absorb the undecomposed 
muriatic acid, there remained one hundred 
measures of chlorine and one hundred and forty 
of hydrogen. In conformity with the law of 
Gay Lussac, the quantities should have been 
equal, but the deficiency of chlorine was justly 
referred to its large absorbability by water. 
The perfect accordance of muriatic acid gas 
with the law of volumes was further shown by 
the observation that the contraction of volume 
in muriatic acid gas electrized over mercury ;— 
a diminution due to the combination of the 
liberated chlorine with mercury,—is precisely 
equal to the quantity of hydrogen gas obtained. 
In 1803 Dr. Henry made known to the Royal 
Society his elaborate experiments on the quan- 
tity of gases absorbed by water at different tem- 
peratures and under different pressures. The 
absorbabilities of the different gases, under a 
constant pressure, by water of 55° Fahrenheit, 
were first accurately measured. Elevation of 
temperature was found to lessen the amount of 
absorption, the diminution for each increment 
of 10° above the standard temperature being 
equivalent to about ;';th of the entire bulk ab- 
sorbable at 55° Ft. In investigating the absorp- ° 
H 
