RESEARCHES UPON SALICIN. 
143 
in the dry or moist state. But the greater number of the 
other acids decompose it by setting force the hydrate of sali- 
cide. It is precipitated of a yellow color by the salts of lead, 
silver, protoxide and peroxide of mercury, manganese, ba- 
ryta, &c. 
The salicide of potassium contains a certain quantity of 
water of crystallization of which it cannot be deprived with- 
out partial decomposition. The water which is disengaged 
when the salicide is heated is always accompanied by a little 
of the hyduret of salicyle. This circumstance prevented me 
from determining exact its water of crystallization. 
The salicide of potassium when anhydrous should be com- 
posed of one equivalent of salicyle and one equivalent of 
metal ; in fact, by double decomposition it yields insoluble 
salicides, having this composition, and the remaining liquid is 
neutral to test paper. 
Salicide of Ammonium. — On placing the hydrate of salicyle 
in contact with concentrated ammonia, the whole becomes a 
yellow crystalline mass soluble in water. On passing gaseous 
ammonia through it, the same phenomena results. In the latter 
case, the salicide of ammonium is presented under the form of 
yellow needles. This compound, both when in vacuo and in 
the open air, is rapidly destroyed. Ammonia is disengaged 
and the oil set free. On this account I was unable to ascertain 
its composition by direct analysis. But it may be deduced 
from the amount of ammoniacal gas which is absorbed by a 
known weight of the hyduret. 
Salicide of Barium. — This salt is prepared by double de- 
composition with a solution of chloride of barium and a con- 
centrated solution of salicide of potassium. The salicide of bari- 
um is precipitated as a crystalline powder of a beautiful yellow 
color. A process is to saturate a hot solution of baryta with 
hyduret of salicyle; the salicide of barium crystallizes on the 
cooling of the solution in yellow needles. It is but little solu- 
ble in water especially when cold. 
I. 0.522 salicide of barium gave 0.292 of sulphate of ba- 
ryta. On the other hand, 
