140 : On definite Proportions. 
a.) Ten grammes of distilled zinc were dissolved in nitri¢ 
acid, and dried and ignited in a platina crucible; the resi- 
due was 12°44 gr. of grayish oxide of zinc, 
b.) Ten grammes of the same zinc, dissolved in nitrie 
acid in a glass flask, dried and ignited, gave again 12°44 of 
oxide. This oxide of zinc, therefore, if we neglect the im- 
purities, consists of 
PING C2 os od ses ee SOSD 100°0 
Oxyeeiis .. 2. 22s PSL 24°4 
c.) Twenty grammes of the same zine were dissolved in 
sulphuric acid ; the apparatus lost *65 gr. 
d.) On repeating the experiment, the loss was °62 gr. 
e.) With diluted muriatic acid, *68 gr. 
According to experiment ¢), 48°8 parts of oxygen answer 
to 6°5 of hydrogen, and water consists of 11°754 hydrogen 
and 88'246 oxygen. 
In experiment e), on the contrary, according to 
which 48°8 parts of oxygen were combined with 6°8 of 
hydrogen, we have 12°23 of hydrogen and 88°77 of oxygen 
for the composition of water. The first of these experi-. 
ments agreeing best with the statical experiment of Biot 
and Arago, I shall consider it as the most correct. Water 
does not therefore consist, as has generally been assumed, 
of 15 parts hydrogen and 85 oxygen, but of 
Hydrogen... 11°754 100°00 13°32 
Oxygen..... 88°246 750°77 100°00 
In an anaiysis of sulphureted hydrogen gas | had found, 
from some less accurate data, the quantity of sulphur 94:2 
to 5°8 of hydrogen ; the calculation, corrected by the pro- 
portions determined in this essay, gave 93°06 of sulphur to 
6:94 of hydrogen. In order to examine the accuracy of 
this result, I dissolved in muriatic acid five grammes of 
sulphuret of iron ‘¢ at a minimum,” which I had obtained 
by igniting in a glass retort the artificial sulphuret at a 
maximum, and conducted the gas which escaped through 
caustic potass. The gas was completely absorbed, without 
leaving the slightest portion of hydrogen gas. When the 
solution was filtered, I found +28 gr. of sulphur remaining. 
Five more grammes of the same sulphuret were changed 
into red oxide of iron, and gave 4°3 gr. answering to 2°98 
of iron. Consequently this sulphuret of iron contained 
2°02 gr. of sulphur, of which 1°74 were consumed in form- 
ing the sulphureted hydrogen gas: 58:4 parts of the sul- 
phur thus employed answerimg to 100 of the iron dissolved; 
supposing at least the superfluaus undissolved sulphur to 
haye been perfectly free from hydrogen and from water, 
after 
