BULLETIN OF THE BUSSEY INSTITUTION. 401 
From the residue left after the action of 1% hydrochloric acid on 
Apricot Stones there was obtained furfurol amounting to 12.78%, of the 
original wood, 7. €., to 23.52% of pentosans. 
Wood Gum, so called. The method of preparing wood gum 
from sawdust as employed by Thomsen* which in its simplest 
form consisted in leaching the wood with ammonia water to dis- 
solve albuminoids and coloring matters, digesting the residue with 
soda lye and mixing the filtrate with rather more than its own 
volume of alcohol, has been put to good use by many observers as 
a means of obtaining material for further study, though at its best 
it can hardly be classed as a quantitative method of analysis, 
because of the fundamental difficulty that the alkali never dissolves 
out from the wood all the xylan which can be shown to be therein 
contained. It is to be remarked, however, that Thomsen’s method 
is to be preferred to the rough and ready process suggested by 
Loew,{ which consists simply in digesting the finely powdered 
wood with ten times its weight of soda lye of five per cent. and 
acidulating the filtrate with hydrochloric acid. 
Misled by the apparent easiness of this plan I have applied it 
in a number of instances until convinced of its defects. The 
prime objection to Loew’s plan is the liability that in the absence 
of alcohol the wood gum will not be precipitated, or at the least 
will not be precipitated completely at the moment when the alkaline 
liquid is acidified. The difficulty is aggravated doubtless by the 
fact that the original alkaline liquid has to be diluted to a con- 
siderable extent with water in order that it may be filtered. But, 
as was noticed by Thomsen,§ wood gum is precipitated by dilute 
acids less quickly and probably less completely than it is precipi- 
tated by alcohol. He remarks that on supersaturating the alkaline 
solution with an acid a precipitate appears after a time, but that 
the precipitate appears immediately when the liquid is mixed with 
an equal volume of alcohol. He observes also that Poumaréde 
and Figuier,|| as long ago as 1847, called attention to the fact 
that it is through the influence of the saline matter which is formed 
* Journal fiir praktische Chemie. 1879 [N. F.], 19. 159-163. 
+ Compare Hoffmeister, Versuchs-Stationen. 48. 406, 409. 
t See Okamura, in Versuchs-Stationen. 45, 433, 437. 
§ Journal fiir praktische Chemie. [N. F.] 19. 150, 166. 
|| Journal fiir praktische Chemie. 42. 29; [N. F.] 19. 148. 
