302 
PROCEEDINGS OF SECTION B. 
external use they are very useful a3 wet applications in the form of 
cold compresses, but there is nothing in their favour compared with 
the gums of the ruby group in this respect. 
Eucalyptus corymbosa , Sm. — This tree, called bloodwood, whose 
foliage does not contain any essential oil, has a persistent bark, and 
yields a gum in great plenty, exuding at times as a bright-red fluid of 
the consistence of treacle. It often becomes imprisoned between the 
layers of the wood, where it gets hard and may be broken out in 
quantity. It varies from being soluble in water to complete 
insolubility in water and alcohol. It dissolves in a fresh state to a 
large extent in cold water, and this solution, when filtered and quite 
clear, deposits, after some standing, a greyish powder insoluble in water 
and alcohol. It consists of ellagie acid, and dissolves in KOH with 
intense yellow' colouration, and with formation of crystals of pota3s. 
glaucomelanate to be easily observed under the microscope. Still 
there is not so much deposited by a 10 per cent, gum solution as by a 
solution of Angophora gum of the same strength, and after the first 
deposit is formed it wants some weeks before a second deposit can be 
taken off. 
Corymbosa gum contains 37 per cent, of soluble tannates. 
Addition of hydrochloric acid brings the tannates down, and after 
some time ellagie acid is formed in the deposit. Chloroform takes it 
out, and fines needles of ellagie acid are formed when the chloroform 
evaporates. The most part of the precipitate formed by hydrochloric 
acid consists of eucalypto-arabin, to which ellago-tannic acid and 
corymbosa-tannic acid is united. If boiled, the bulky mass collapses 
very much. Alcohol takes the phlobaphenes out of it; metarabin and 
ellagie acid are left. Cold KOFI takes the ellagie acid out of the 
metarabin, which dissolves w’hen boiled in the KOH solution. 
The tannin proper to the gum of E. corymbosa (besides the 
ellago-tannic acid) is obtained pure by throwing out first the 
ellago-tannic by HC1, then by precipitating the other tannin with salt 
or by the addition of more HOI, and by extracting this last precipitate 
with acetic ether. Its reactions are similar to those of the diluted 
corymbosa gum solution. Ferric salts produce a light-blue, turned 
into Indian red by addition of liquid ammonia ; ferrous salts stain the 
solution bright blue ; copper acetate produces a greenish-brown, as 
most of the other reagents do. If boiled w r ith dilute hydrochloric 
acid this tannin forms a phlobaphene nearly allied to the phlobaphene 
of Angophora gum. Dry distillation yields pyro-gallol. 
The residue in the watery solution of corymbosa gum does not 
contain any eatechin. The turbidity of the boiled solution is due to 
debris of the bark, and to ellagie acid insoluble in spirits. The 
medicinal value of this gum is not so high as that of the Angophoras. 
It may be used in the same way as the gum of those, but perhaps in 
a stronger dose, as I found by experience. 
Eucalyptus maculata , Hook. — The spotted gum is a tall tree with 
deciduous bark and plenty of oil-cells in the leaves, which yield an 
essential fragrant oil, especially in the variety E. citriodora . The 
Wounded bark throws out a brown treacle-like gum, which hardens 
into large masses. When these are disturbed they give off an aroma-like 
