66 Mr . Davy's Lecture on some new analytical Researches 
intense ignition produced by the action of the two bodies, and 
one eighth of a cubical inch of gas was disengaged, which 
was sulphuretted hydrogene. The compound was exposed in 
a mercurial apparatus to the action of liquid muriatic acid; 
when a cubical inch and quarter of aeriform matter was pro- 
duced, which proved to be pure sulphuretted hydrogene. 
The same experiment was repeated, except that four grains 
of sulphur were employed instead of one. In this case, a 
quarter of a cubical inch of gas was disengaged during the 
process of combination ; and when the compound was acted 
upon by muriatic acid, only three quarters of a cubical inch of 
sulphuretted hydrogene was obtained. 
Now, sulphuret of potash produces sulphuretted hydrogene 
by the action of an acid ; and if the sulphur had not contained 
oxygene, the hydrogene evolved by the action of the potas- 
sium in both these experiments ought to have equalled at least 
two cubical inches, and the whole quantity of sulphuretted 
hydrogene ought to have been more : and that so much less 
sulphuretted hydrogene was evolved in the second experiment, 
can only be ascribed to the larger quantity of oxygene fur- 
nished to the potassium by the larger quantity of the sulphur. 
I have made several experiments of this kind with similar 
results. Whenever equal quantities of potassium were com- 
bined with unequal quantities of sulphur, and exposed after- 
wards to the action of muriatic acid, the largest quantity of 
sulphuretted hydrogene was furnished by the product con- 
taining the smallest proportion of sulphur, and in no case was 
the quantity of gas equal in volume to the quantity of hydro- 
gene, which would have been produced by the mere action of 
potassium upon water. 
