434 On the different Compounds formed by the 
cels; the first did not differ from the others, only iu con- 
taining an excess of sulphuric acid. That this excess of 
acid might not decempose the vegetable mattcr in solution, 
I only reduced the liquor to one-fourth of its original quan- 
me Jn this state, it appeared green by reflection, and 2 
yellowish red by refraction; (a phenomenon similar to what 
takes place in the solution of nephritic wood, with this 
difference, that the latter appears blue by reflection;) it 
precipitated gelatin, whence it 1s evident that it contained the 
tanning substance of Hatchett. To separate this latter 
from the sulphuric acid, I saturated it with barytes water. 
The sulphate was precipitated, and the combination of the 
astringent matter and barytes remained in the liquor: this 
was Of a fine red colour: when muriatic acid was poured 
upon it to saturate the barytes, it regained the property of 
reflecting green, and parted with the rose colour: thus sa- 
turated, it precipitated gelatin; the combination of astrin- 
gent matter and barytes, being dried and afterwards heated 
in a glass tube, was converted into a sulphuret. 
The second parcels of water contained an exceedingly 
small quantity of sulphuric acid: to separate this, I poured 
Into it a few drops of the combination I have mentioned, 
(of the astringent matter and Larytes) and filtered it. The 
filtered liquor might be considered as a solution of pure 
astringent matter. It was acid, and presented the same 
appearances to the light as the first washing when concen- 
trated ; it precipitated gelatin; evaporated to dryness, there . 
remained a substance, from which, when subjected to heat, 
there were disengaged sulphuretted hydrogen gas and sul- 
phurous acid. The astringent matter had undergone some 
alteration by this evaporation; for, treated with water, it 
formed a solution which no longer reflected a green colour, 
and which precipitated barytes in brown floccules. This 
precipitate was soluble in nitric acid, and was converted into 
a suiphuret by calcination. ' 
I regard the astringent matter as being composed of 
sulphuric acid, and a certain substance which at present is 
anknown to me. It is true, I have not been able directly 
to separate the sulphuric acid; but as I cannot detect in it 
either sulphuretted hydrogen or sulphurous acid, and as on 
the other hand it reddens turnsole, and contains oxygen 
and sulphur, the former opinion appears to me in the pre- 
sent state of scicnce to be the most probable. 
Recapitulation. 
When sulphuric acid is distilled from camphor, there are 
obtained, 
