CONSTITUENTS OF THE SAP OF THE SILKY OAK. 197 
Ist fifth =. 31-1 
ond ,, = 25:0 
od ow 1a 
wae 7S uP ae 
5th NES 
”? 
this represents 97:5 per cent. of total acids originally in the retort. 
The characteristic feature of butyric acid, in distilling over in 
greater proportion in the first divisions of the distillate, is well 
marked in the results obtained from this sap, and it thus differs 
from acetic acid which gives less acid to the first portions of the 
distillate than to each succeeding one. 
From a determination of the barium salt of a portion of the 
distillate from the sap, and weighing as BaSO, it was found that 
the percentage of barium sulphate was 79-2, while the theoretical 
quantity from barium butyrate is 74-91. 
From the above results of the odour, the ethereal product, the 
rate of distillation, and the percentage of barium sulphate, it is 
apparent that the greater portion of this volatile acid is butyric 
acid, although the indications obtained by the result of the dis- 
tillation, and also the barium determination, point to the presence 
of a small quantity of acetic acid. . 
The amount of fixed organic acid, other than the brownish 
humic-like material, is very small. Special effort was made to 
detect, if possible, the presence of malic acid, but the evidence 
obtainable from the small quantity of material received does not 
Point to the presence of malic acid in the sap of Grevillea robusta. — 
A very slight precipitate was obtained by adding alcohol to the 
Prepared solution in‘which the absence of oxalic, tartaric, and 
Citric acids had been determined. The usual tests with this pre- 
cipitate pointed rather to the presence of succinic acid than to 
that of malic acid. As the acid is present in such small quantity 
much more material would be needed to satisfactorily determine it. 
It is very evident, therefore, that the formation of the succinic 
acid found in the deposit in this tree, previously described, was — 
