164 ON THE FRUIT OF DIOSPYROS VIRGINIANA. 
of tannin, such as is obtained from the oak bark. The pre- 
cipitate with sub-acetate of lead, after standing for 
some time, changed its colour from white to orange, and 
then to dark brown, and this is particularly mentioned by 
Berzelius to be a property of the tannate of lead, and^the cer- 
tain test for this substance is the solution of gelatin, which 
is dissolved by most of the weak acids, but which precipi- 
tates tannin. The astringent matter of the persimmon is 
therefore inferred to be tannin, and tannin analogous to 
that of the oak bark, and not modified tannin, and it is also 
supposed that at this period of its growth tannin is the only 
active substance in the persimmon besides a trace of malic 
acid. The insoluble substance left after the evaporation of 
the tincture, is probably the apotheme which is formed 
when nearly all of the tinctures or infusions of vegetable 
astringents are exposed to the influence of the air ; it agrees 
entirely in its properties with the description of apotheme 
which is given by Berzelius. There is neither starch, gum, 
nor resin, in the fruit. 
(3.) A month after the last experiments a tincture was 
made of some freshly gathered persimmons ; they were by 
this time about an inch in diameter ; the colour was chang- 
ing from a deep green to a light red; they were full of juice, 
very sweet, and excessively astringent. They contained 
all the substances found in those before experimented upon, 
but neither starch nor gum. 
(4.) Some persimmons were gathered, as ripe as could be 
obtained, and after having been exposed to the frost, they 
were of a rich salmon colour, very sweet and juicy, and 
had entirely lost their astringency ; 6S0 grs. of these persim- 
mons were submitted to the action of alcohol ; the tincture 
was filtered and evaporated; during the evaporation it did 
not become gelatinous, as in the former experiments, but 
thickened at once to a syrup, and was dried to the consis- 
tence of an extract ; it was the same as the saccharine mat- 
ter obtained before, analogous to grape sugar, and weighed 
