BULLETIN OF THE BUSSEY INSTITUTION. 45 
may be drenched with strong alcohol after the acid has had time 
to act. After filtering, the alcohol is expelled, the excess of acid 
is neutralized, and the phenylhydrazin test applied. When car- 
bonic acid gas was used for decomposing the mannose-lead pre- 
cipitate particularly clear solutions were obtained. In this case, 
the filtrate from the lead carbonate was evaporated to a thick 
syrup which was treated with alcohol, somewhat diluted (3:1), 
and again filtered. After expelling the alcohol, the aqueous solu- 
tion was tested with phenylhydrazin. Trials with oxalic acid as 
the agent for decomposing the mannose-lead precipitate went to 
show that, while a cold solution of one part oxalic acid in ten 
parts of water gave good results, the use of this acid was, on the 
whole, rather less satisfactory than that of either of the other 
acids above mentioned. 
In conducting this research I have been most ably seconded by 
my assistant, Mr. F. T. Dillingham. To him my best thanks are 
due. I am indebted also to my former assistant, Mr. H. W. 
Haynes, who labored with me assiduously in tentative efforts 
which opened the way to an easier and more accurate method of 
distinguishing mannose-hydrazone than was at that time known 
to us. 
