120 PROCEEDINGS OF THE SCIENTIFIC ASSOCIATION. 
The juice, although at first nearly neutral, quickly 
becomes acid, and was always so at the time of distillation. 
In some of the earlier experiments sulphuric acid was 
added to the contents of the retort, usually after all the free 
prussic acid had passed over; but the yield was not found to 
be influenced by this treatment. 
The high temperature prevailing in this climate rendered 
it necessary to prove that prussic acid could be isolated by 
distillation from dilute solutions without loss. Aqueous 
prussic acid, therefore, was prepared, and diluted until 20cc., 
made up to 200ce. with water, would furnish a solution 
containing about twice the quantity found in the liquid 
strained from the roots. Two such mixtures having been 
made, the prussic acid in one was estimated directly, and in 
the other after distillation. The following results were 
obtained — 
II C N in 200 cc. of Solution. 
I. Not distilled ’06824 grm. 
II. Distilled -06744 „ 
Corrected temperature of water passing from condenser, 
25*2°c. ; of laboratory, 27°c. ; this temperature being usual. 
A second trial was made by diluting 20cc. of the same 
prussic acid to 500cc. Two portions of 200cc. were 
measured, and the prussic acid in each estimated as before. 
H C N in 200<?c. of Solution. 
I. Not distilled *02734 grm. 
II. Distilled *02726 „ 
A final experiment determined whether a known quantity 
of prussic acid, added to the diluted juice , suffered loss by 
distillation. The juice used had not been distilled, or 
deprived of the prussic acid naturally present, but this was 
