1817.] during the Year 1816. 53 
having a vessel of silver adapted to its inside, and having a tube 
proceeding from its top connected with a set of Woulf’s bottles, in 
order to collect the liquid products that come over. The vegetable 
substance is put into this digester first with water; and when that 
liquid has extracted every thing that is soluble, the same process is 
repeated with alcohol. ‘The advantage of the apparatus is, that the 
heat of these liquids may be increased considerably above the boil- 
ing point, which enables them to exert a more powerful solvent 
energy. The analysis of cork was given as an example of this 
method. 
Cork, when treated in this manner with water, gave out an 
aromatic principle, and a little acetic acid, which passed over with 
the water into the receiver. The extract formed by the water con- 
tained two colouring matters, the one yellow, the other red; an 
acid, the nature of which was not determined; gallic acid; an 
astringent substance; a substance containing axote; a substance 
soluble in water, and insoluble in alcohol; gallate of iron; lime ; 
and traces of magnesia: 20 parts of cork thus treated by water left 
17°15 of insoluble matter. 
The undissolved residue, being treated a sufficient number of 
times with alcohol in the same apparatus, yielded a variety of bodies, 
but which seem reducible to three; namely, cerin, resin, and an 
oil. 
Cerin is a name which Chevreul has thought proper to give a 
crystallized substance that precipitates gradually when the alcohol 
digested on the cork is concentrated to one sixth of its bulk, and 
then set aside. ‘The name is unfortunate, as it had been already 
applied by John to that part of common wax which dissolves in 
alcohol. The insoluble part of wax he had denominated myricine. 
If, therefore, the new substance of Chevreul be different from the 
cerin of John, as would appear to be the case from his experiments, 
it will be necessary to contrive a new name for it. Cerin is white, 
and in small needles. It does not melt in boiling water, but be- 
comes soft, and sinks to the bottom of that liquid; while wax 
melts at 145°, and swims upon the surface of water. When heated 
or distilled, it undergoes nearly the same changes as wax. It is 
rather more soluble in alcohol than wax; 1000 parts of boiling 
alcohol dissolving, according to Chevreul, 2°42 parts of cerin and 
only two parts of wax. Nitric acid gradually dissolves it, and con- 
verts a portion of it into oxalic acid. It did not dissolve in an 
alcoholic solution of potash. 
The 20 parts of cork thus treated with alcohol and water still 
weighed 14 parts. ‘They consisted of suber, but not in a state of 
complete purity. (Ann. de Chim, xevi. 141.) 
6. Action of Tannin on Mucilage.—Grassmann has published a 
set of experiments showing that when infusion of nutgalls, or any 
other liquid containing tannin, is mixed with a vegetable mucilage, 
a precipitate falls, which he calls tannate of mucilage. The muci- 
