for 1790 (vol. lxxx., p. 273).

Tabasheer is said to be sometimes found among the ashes of bamboos that
have been set on fire (by mutual friction?). Ordinarily, however, it is
sought for by splitting open those bamboo stems which give a rattling
sound when shaken. Such rattling sounds do not, however, afford
infallible criteria as to the presence or absence of tabasheer in a
bamboo, for where the quantity is small it is often found to be closely
adherent to the bottom and sides of the cavity. Tabasheer is by no means
found in all stems or in all joints of the same stem of the bamboos.
Whether certain species produce it in greater abundance than others, and
what is the influence of soil, situation, and season upon the production
of the substance, are questions which do not seem as yet to have been
accurately investigated.

Dr. Russell found that the bamboos which produce tabasheer often contain
a fluid, usually clear, transparent, and colorless or of greenish tint,
but sometimes thicker and of a white color, and at other times darker and
of the consistency of honey. Occasionally the thicker varieties were
found passing into a solid state, and forming tabasheer.

Dr. Russell performed the interesting experiment of drawing off the
liquid from the bamboo stem and allowing it to stand in stoppered
bottles. A "whitish, cottony sediment" was formed at the bottom, with a
thin film of the same kind at the top. When the whole was well shaken
together and allowed to evaporate, it left a residue of a whitish brown
color resembling the inferior kinds of tabasheer. By splitting up
different joints of bamboo Dr. Russell was also able to satisfy himself
of the gradual deposition within them of the solid tabasheer by the
evaporation of the liquid solvent.

In 1791, Mr. James Louis Macie, F.R.S. (who afterward took the name of
Smithson), gave an account of his examination of the properties of the
specimens of tabasheer sent home by Dr. Russell (Phil. Trans., vol.
lxxxi., 1791, p. 368). These specimens came from Vellore, Hyderabad,
Masulipatam, and other localities in India. They were submitted to a
number of tests which induced Mr. Macie to believe that they consisted
principally of silica, but that before calcination some vegetable matter
must have been present. A determination of the specific gravity of the
substance by Mr. Macie gave 2.188 as the result. Another determination by
Mr. Cavendish gave 2.169.

In this same paper it i