566 
seem not very conclusive. By a process of fermentation, alcohol 
and a number of other compounds of well established composition 
may be obtained from mannite ; hut inasmuch as disintegration 
takes place in this process, the formulas of the products afford no 
guide to the constitution of the original body. 
Up to the present time no compound of known formula has been 
got from mannite by other than disintegrating processes. 
The uncertainty about the real composition of mannite has finally 
been illustrated by Berthelot, who in his “ Chimie organique fondee 
sur la Synthese,” has proposed the formula, 
c 3 h 7 o 3 . 
Berthelot has supported his view by bringing forward a number 
of salts of mannite, and has hinted at the possibility of preparing 
the substance from allyl compounds. 
The reaction we have to bring forward in this paper is in contra- 
diction to Berthelot. By distilling mannite with a great excess of 
strong hydriodic acid, in a stream of carbonic acid gas, it is almost 
completely resolved into Iodide of Hexyl. The change may be 
thus represented : — 
Mannite. 
C'«H 8 (H0) # + 11HI. 
Iodide of Hexyl. 
rC 6 H 1 ?I + 6H 2 0 + I II , 
This reaction is conclusive against Berthelot’s formula, for it 
cannot be maintained that an easy reduction with hydriodic acid 
would increase the complexity of the carbon molecule. A parallel 
reaction between glycerine and hydriodic acid was observed by one 
of us some time ago.* 
Glycerine. 
C 3 H 6 (HO) 3 +5HI = 
Iodide of Propyl. 
C^I + 3H 2 0 + I 4 . 
We are thus conducted to the result : mannite is the hexatomic 
alcohol of the C g series, or, as we prefer to write, Mannite is 
* Erlenmeyer. Eeitscinift fur Chemie u. Pharmacie. 
