628 DR J. J. DOBBIE AND MR G. G. HENDERSON 
The melting point of the specimen marked “ Pontianak, Dutch East Indies, 
probably Calamus,” is only slightly under 100° C, nearly 40° above that of the 
Socotra resin, and 20° above that of Calamus Draco. When decomposed by 
heat it gives off non-irritating fumes. The alcoholic solution is of a pink-red 
colour, and has an acid reaction. Benzoic acid and cinnamic acid are absent. 
In cold strong caustic soda it dissolves with a magnificent purple colour, which 
changes on heating or dilution to an orange-yellow. It is readily soluble in 
ammonia, giving the same colour as with soda. It is also much more soluble 
than either the Socotra resin or that from Calamus Draco in lime water. In cold 
sodium carbonate it dissolves with effervescence to a beautiful purple-pink or 
mauve-pink solution, which changes to orange-red on boiling. Acetate of lead 
gives a lilac coloured precipitate, soluble in alcohol and apparently slightly 
soluble in boiling water. This resin is much more soluble in hydrochloric acid 
than either of the preceding, and is reprecipitated from this solution, as well as 
from its solution in aeetic acid, on neutralisation with ammonia. It is decom- 
posed by strong nitric acid. ‘Two combustions gave the following results :— 
(1) (2) (Mean. ) 
C 68:18 68'22 68°20 
jal 6:01 6:05 6:02 
O 25°81 25°74 25°78 
100 00 100-00 100:00 
This resin therefore appears to contain a somewhat lower percentage of carbon 
than the preceding, and would correspond better with the formula C,,H,,O; than 
with that which we have assigned to the Socotra resin. A substance having the 
above formula would contain 67:54 per cent. of carbon, 5°96 per cent. of 
hydrogen, and 26°52 per cent. of oxygen, and would have a combining weight 
of 302. Owing to the very small quantity of this resin we had to work upon, 
we were not able to confirm these results by the analysis of any salts. 
The resins belonging to our third class are peculiar. We selected for 
examination one of the Kew specimens marked “Penang.” In common with 
the other resins which we have placed in this class it is soluble for the most part 
in chloroform, benzene, and carbon bisulphide. A portion, however, persistently 
remains undissolved by the carbon bisulphide, and carbon bisulphide gives a 
precipitate when added to the solution in chloroform. These resins therefore 
would appear to be composed of a mixture of two resins, one soluble in chloro- 
form, benzene, and carbon bisulphide, the other soluble in chloroform and 
benzene, but insoluble in carbon bisulphide. This conclusion is confirmed by 
the varying results obtained by combustion. The part of the resin soluble in 
chloroform, benzene, and carbon bisulphide corresponds very closely in all its 
properties with the resin from Calamus Draco, and like that resin gives a subli- 
