1647 
On illuminating a solution of benzophenone in moist ether a liberal 
formation of pinacone and aldehyde was noticed. 
4C,H,COC,H, + (C,H,),0 + H,O = 2/(C,H,),COH), + 2C,H,O 
Hence, the photo-reaction has here induced the alcohol formation 
and this notwithstanding the retarding action of water which at 
the commencement was present in considerable quantities. 
The experimental details will be published elsewhere. 
Chemistry. — “The hydrogen-ion-concentration of some complex 
polyhydroxyborate solutions,’ By Prof. J. BörseKeN and 
A. H. KerstveEns. 
(Communicated in the meeting of March 25, 1916). 
The relation found by one of us between the influence exerted 
by a number of polyhydroxy-compounds on the electric conductivity 
of boric acid, (rendering it possible to get some more information 
as to the configuration of these compounds) made it desirable to 
further trace the cause of the change in conductivity. From what 
was found (which, moreover, was already known from observations 
of other workers) boric acid frequently becomes a more powerful 
acid, and the increase in the concentration of the H-ions must, 
therefore, be considered as being the most important cause of the 
exaltation in conductivity. 
Slight decreases in conductivity have, however, also been noticed 
which may then be attributed on the one hand to the formation of 
complexions with small migration constants, on the other hand toa 
greater viscosity of the medium. 
We have now in the first place made it our task to determine 
the H-ion concentration of a few diverging cases and to compare 
these values with those which could be calculated from the determi- 
nations of the conductivity. 
The H-ion concentration was deduced from the electromotoric 
force of a concentration chain which was determined according to 
the compensation method of PogGenporr with the capillary electro- 
meter of LippMANN as zero-instrument. 
The complex boric acid solution investigated by us formed part 
of the concentration chain: 
H, (p =1 atm.) | Cr- | satur. KCl | Hg,Cl, in 0.1 n. KCI | He. 
In view of the smali H-ion concentration the vessel, containing 
