Hydrogen and Carbon. . 263 
for temperature, nor the state of the barometer; because 
air and all gases undergo the same change of bulk, by 
changing the temperature and the pressure. The gas is al- 
ways weighed, saturated with moisture. This is corrected 
when requisite by the table of Dalton. In this way the 
flask may be easily weighed, true to the -25dth part of a 
grain; so that you are always sure of the specific gravity of 
the gas, to the 3d decimal figure. The specific gravity of 
common air is always taken 1-000, and at the temperaiure 
of 60°, barometer at, 30 inches, 100 cubic inches of it 
weigh 30°5 graius. These data enable us to determine the 
weight of 100 cubic inches of any gas whose specific gra- 
vitys known, Mr, Dalton found the specific gravity of 
this gas 0-600. I took its specific gravity more than once, 
and collected at different times, bat never found it beavier 
than 0°5554. 
6. The gas from stagnant water burns with a yellow 
flame, more reaqily, aad with a larger flame than any other 
combustible gas, except olefiant gas, and the vapour of ether. 
7. When mixed with oxygen gas, aud kindled by an 
electric spark, it detonates londly, and undergoes: a consi- 
derable diminution of bulk. Its combustibility by this pro- 
cess 18 confined within very narrow limits. It does not 
burn uniess the bulk of the oxygen rather exceeds its own 
bulk, and it ceases to burn when the oxygen gas is more 
than 2; times the bulk of the inflammable gas. The limits 
of combustion, according to my trials, are 100 measures 
of inflammable gas, and 103 or 227 measures of oxygen 
gas. A mixture of 100 measures of inflammable gas, with 
232 or 292 measures of oxygen gas, does not burn. 
8. A good many experiments on the combustion of this 
gas with oxygen by clectricity give the following general 
result} 100 measures of the inflammable gas consume 205 
Tmuecasures of oxygen vas, and s04 measures of carbonic 
acid gas are formed. This result very nearly agrees with 
the experiments of Mr. Dalton, who found, as I have been 
informed by Dr. Heury, that 100 measures of this gas re- 
quire for combustion 200 measures of oxygen gas, and 
forn: 100 measures of carbonie acid. The following table 
contains a few of the experiments which | made upon this 
gas. The others were precisely of the same kind, and co- 
incided with these as nearly as possible. 
The oxygen gas used contaimed 12 percent. of azote. 
It had been prepared from hyper-oxymuriate of potash, and, 
when recent, contained only 1 per cent. of azote. It had 
been kept above a year in acrystal bottle well stopped ; 
Ra ‘ but 
