354 M. Berxelius on the [Nov. 
hours, except under strong pressure. In the experiments which 
I performed to discover the nature of this body, I found that the 
best method of obtaining it is to pour the saturated hepar (AS!°) 
by small quantities at a time, into a warm mixture of muriatic 
acid and water. The acid should be neither too much concen- 
trated nor too dilute. The heat is so far from accelerating the 
decomposition, that it causes the separated body to remain in 
drops; and although a little sulphuretted hydrogen is disen- 
gaged, and sulphur deposited in the solution, the greater part 
nevertheless consists of this oil, which has a yellowish colour, 
and which, when the experiment succeeds well, is nearly trans- 
arent. This oil, afterwards heated in an acid, suffers a little 
sulphuretted hydrogen to escape; but a small quantity only is 
decomposed, before the water begins to boil, and then the aque- 
ous vapour conducts a little sulphuretted hydrogen. When 
collected on a filter, it has the appearance of an oily substance ; 
it is not very fluid, and does not become solid till some days 
have elapsed ; it has a peculiar disagreeable smell, totally differ- 
ent from that of sulphuretted hydrogen ; when it is heated, it 
affects the nose and eyes nearly in the same way that cyanogen 
does. Similar effects are produced by the vapours of the acid 
liquor when the oily substance is boiled in it; if it be received 
upon a cold body, the drops become milky, and the effects are 
particularly evident after the free sulphuretted hydrogen is eva- 
porated from the liquor. 
The composition of this body cannot be determined with cer- 
tainty. The circumstances of its preparation show that it 
contains at the period of its formation at least five atoms of 
sulphur for two atoms of hydrogen; and that it afterwards 
undergoes a change in the proportions of its constituent parts, 
by the loss of sulphuretted hydrogen. It resembles the peroxide 
of hydrogen in this circumstance, that by admixture with water, 
it is gradually resolved into sulphuretted hydrogen and sulphur; 
treated in the cold with an alkali, it almost immediately becomes 
fixed; the alkali unites with the sulphuretted hydrogen, and 
leaves the sulphur. It is remarkable that the compound of sul- 
phur and hydrogen of the hepar. at a maximum, or which is 
formed there, consists of 2 JJ + 5 S, and that it is consequently 
similar in composition to nitric acid 2 A z+5 O, and probably 
to the arsenic and phosphoric acids. 
If, on the other hand, we suppose that the alkaline sulphurets 
are dissolved in water without their being decomposed, it fol- 
lows that no similar hydrosulphurets exist; the compounds of 
hydrogen and sulphur in so many proportions are scarcely neces- 
sary; but an acid poured upon the hepar produces upon the 
sulphuret of potassium the same effect as upon the sulphuret 
of iron, and the sulphuretted hydrogen is formed only at that. 
moment. The effect of the acid upon the dry hepar is, \per- 
fectly similar, to that produced upon the dissolved hepar. | It, 
