296 
PROCEEDINGS OF SECTION B. 
washing the precipitate in spirits the phlobaphene is separated from 
the metarabin, which, through the action of alkalies, is obtained 
soluble again. In this purified state it is precipitated by acetate of 
copper, which shows its near relation to vegetable slime. Indeed, a 
mucous digestion of sideropliloia gum is obtained sometimes instead 
of a clear solution, if the gum is very slowly dissolved by cold water 
in the winter time. 
(2.) The tannin of the sideropliloia gum and of the gums belonging 
to this group might be called gum tannin. By different assays, 
including Lowenthal’s process, I found the percentage in quite fresh 
undried gum not to be more than 28. The tannin is not related at 
all to the tannin of the Malabar kino— is not kino-tannic acid. 
By dry distillation it yields only pyro-gallic acid and no catechol, as 
the following experiment shows : One grain of sideropliloia gum is 
heated for twenty minutes in three grams of pure glycerine to 200° C. 
A deep-brown solution of syrup consistence is produced, which is 
diluted after cooling with 20 grams of distilled water. Twenty grams 
of pure ether are added ; the whole is well shaken and the ether taken 
off, out of which pyro-gallic acid is obtained in fine colourless needles, 
easily recognised when dissolved in water and acted upon by ferrous 
sulphate and limewater. As the arabin is liable to add impurities 
from a dry distillation,’ * I repeated the experiment with purified 
sideropliloia tannin and got the same results. The purple colour was 
still more distinct on addition of limewater to the pyro-gallic acid, 
obtained from the purer tannin. There are many reactions which 
establish a wide gap between kino-tannic acid and the tannin of the 
sideropliloia group. The albumen of blood serum and fresh albumen 
of eggs is precipitated quickly by kino — very slowly by the tannin of 
sideropliloia gum, resembling in this respect the querei-tannie acid. 
The gum tannin is obtained in a pure state by saturating the 
solution of sideropliloia gum with common salt, shaking it with acetic 
ether, and eliminating the Eucalyptus arabin through the addition of 
alcohol. The acetic ether is evaporated, and the gum tannin is 
dissolved in water. Its characteristic reactions are as follow : Caustic 
potash stains the solution pink ; acetate of copper makes a dark-brown 
precipitate ; copper sulphate gives a slight precipitate, which turns 
dark-brown by addition of ammonia. Limewater gives a pink or red- 
brown precipitate, whereas oak tannin gives a brown, and gallo- tannic 
acid a pale, precipitate, turning blue. Ammon, molybdate in nitric 
acid makes a dark-brown precipitate (gallo-tan., yellow colouration; 
oak tannin, greenish). Sodium sulphide gives a pinkish mixture (oak 
bark, brown ; gallo-tannin, yellow). Lead nitrate makes a pink 
precipitate (oak bark, brown; gallo-tannin, white pr.). Acetate of 
uranium gives a brown precipitate like oak bark ; gallo-tannin, crimson 
solution and brown precipitate. 
The reactions come near those of querci-tannic acid, but they are 
all lighter, more pink than brown. From gallo-tannin it differs widely 
by giving a whitish phlobaphene when boiled with dilute hydrochloric 
acid. This phlobaphene is soluble in alcohol, and gives a pink solution 
with caustic potash. It has nothing to do with the phlobaphene of 
kino-tannic acid, which dissolves only slightly in alcohol and caustic 
potash. The gum tannin solution, by standing a long time, makes a 
