OF SULPHURIC ACID UPON VARIOUS CLASSES OF VEGETABLES. 
471 
FucusoL 
It has been satisfactorily ascertained by various experimenters that furfurol is not 
produced by the action of acids on either the amylaceous or saccharine portions of 
the vegetables which yield it. Neither do the lignine, the gluten or the other nitro- 
genous principles of plants, at all contribute to its formation. The source of furfurol 
requires to be referred therefore to some other very generally diffused proximate prin- 
ciple. Dr. Fownes has thrown out the conjecture, that the substance which yields 
furfurol is the matiere incrustante of M. Payen, viz. the matter with which the interior 
of the cells of plants is lined. This is a hypothesis which I feel disposed to regard 
as exceedingly probable, though it must be confessed that the matiere incrustante is 
not a simple proximate principle, but consists, according to M. Payen, of four kindred 
substances, no one of which the present state of our knowledge enables us with any 
great degree of certainty to prepare absolutely pure. 
Now as it appeared very probable that the matiere incrustante of the different great 
classes of plants would be found on examination to be analogous but not identical, I 
thought it likely that the oils derivable from them would also prove not identical with 
furfurol, though probably very analogous to it in their nature and properties. The 
Algae therefore, as possessing a structure which differs very widely from ordinary her- 
baceous plants, were selected in the first instance as a very good test of the truth of this 
hypothesis. A quantity of the commonest sea-weeds, consisting chiefly of Fucus no- 
dosus, F. vesiculosus, F. serratus, &c., were cut into pieces and introduced along with 
a good deal of sulphuric acid diluted with two parts of water, into the apparatus de- 
scribed in a preceding part of this paper. Steam was then passed through the mixture 
during sixteen to eighteen hours, so long indeed as the liquid which distilled over 
appeared to contain any considerable amount of oil. The acid liquor which collected 
in the receiver was nearly neutralized with pounded chalk, and the oil separated 
from it exactly in the same way as with furfurol. 
The crude oil from Fuci, which I shall call fucusol, always contained a considerable 
amount of acetone, which required to be removed by washing it with water, carefully 
rectifying it at a low temperature, and rejecting the first portions of the oil which 
distilled over. I may mention in passing, that I have invariably found acetone to be 
a constant product, and that to a considerable extent, of the action of sulphuric acid 
upon vegetable substances. Crude fucusol also contains a quantity of meta-furfurol, 
or at any rate of a very similar oil, from which it requires to be freed by being re- 
peatedly rectified along with water, precisely in the same way as furfurol. The sea- 
weeds yielded only about a fourth part of the oil which a similar quantity of bran 
would have done. 
When dried by standing over fused chloride of calcium and then rectified, fucusol 
possesses the following properties. When newly distilled it is nearly colourless, but 
in a few days, especially if exposed to the light, it becomes brownish yellow, and in 
the course of a few weeks of a deep brown colour. If the fucusol is not quite free 
