192 Mr. Faraday on the condensation of 
clean end of the tube in a mixture of ice and salt, warming 
the other end if necessary by a little water, sulphuretted hy- 
drogen in the liquid state distilled over. 
The liquid sulphuretted hydrogen was colourless, limpid, 
and excessively fluid. Ether, when compared with it in similar 
tubes, appeared tenacious and oily. It did not mix with the rest 
of the fluid in the tube, which was no doubt saturated, but re- 
mained standing on it. When a tube containing it was opened, 
the liquid immediately rushed into vapour ; and this being 
done under water, and the vapour collected and examined, 
it proved to be sulphuretted hydrogen gas. As the tempera- 
ture of a tube containing some of it rose from o° to 45 0 , part of 
the fluid rose in vapour, and its bulk diminished ; but there 
was no other change : it did not seem more adhesive at o c than 
at 45 0 . Its refractive power appeared to be rather greater than 
that of water ; it decidedly surpassed that of sulphurous acid. 
A small gage being introduced into a tube in which liquid 
sulphuretted hydrogen was afterwards produced, it was found 
that the pressure of its vapour was nearly equal to 1 7 atmo- 
spheres at the temperature of 50°. 
The gages used were made by drawing out some tubes 
at the blow-pipe table until they were capillary, and of a 
trumpet form ; they were graduated by bringing a small 
portion of mercury successively into their different parts ; 
they were then sealed at the fine end, and a portion of mer- 
cury placed in the broad end ; and in this state they were 
placed in the tubes, so that none of the substances used, or 
produced, could get to the mercury, or pass by it to the in- 
side of the gage. In estimating the number of atmospheres, 
one has always been subtracted for the air left in the tube. 
