71 
We may therefore conclude with great certainty that the isomer 
with the higher melting point is the trans diol, the one with the 
lower melting point the cis diol. 
Then the conduct of the two diols in relation to boric acid was studied. 
In effect it was found that the cis diol considerably augmented 
the conductivity of boric acid while the trans diol caused a small 
depreciation. 
The boric acid method therefore proves to yield a positive result 
only in the case of the OH-groups being situated near to each other. 
So now we can say with complete certainty that hydrindene diol 
(see former communication) m.p. 108°, which increases the conductivity 
of borie acid, is cis-hydrindene diol, while the one with the high 
melting point (159°) is the trans isomer without any doubt. The last 
substance exercises a small decrease of conductivity of borie acid. 
By a communication of E. Fiscnrr (B. 28, 1146, 2496 (1895) on 
the ready formation of cyclic additional compounds of polyaleohols 
with aldehydes and ketones, one of us (Cur. vAN Loon.) has been 
incited tostart an investigation about the conduct of these stereoisomeric 
diols in regard to acetone. . 
Here five- (or six) membered rings are formed of the following type : 
-—C—O 
| CCH). 
Bs ple ea 
Though not certain, it is however highly probable that with this 
condensation the decisive C-atoms are left alone so that here too a 
rearrangement in the sense of the WatLbDEN inversion is out of the 
question. 
With surprising ease the expected condensation product was formed 
from cis hydrindene diol as well as from cis cyclopentane diol, while 
the trans-compounds under the same circumstances [the diols were 
set apart for 24 hours with a twenty-fold quantity of pure acetone 
containing 1"/, HCl] reinained absolutely unchanged. 
We immediately made use of this method to have the configuration 
of the cyclohexane diols fixed. 
These two compounds were obtained 
1. by the action of potassium hydroxide on cyclohexene iodhydrin 
according to Brune, during which action the oxide may be regarded 
as an intermediate product. — This diol melting at 104° was taken 
for the cis diol by Bruner, because it originated from the oxide. 
