Intelligence and Miscellaneous Articles. 235 
When the atomic weight of chloride of zthyle =64°5 is divided 
by the vapour density of this substance, 2°22, the quotient is 
=29°0. This result indicates a condensation to four volumes. The 
theoretical density of the vapour of chloride of zthyle is therefore 
64°5 ; 
36°58 = 2°233. 
When the atomic weight of chloride of titanium =96 is divided 
by the vapour density of this substance = 6°8, the quotient ob- 
tained is 14:12. This number indicates a condensation into two 
volumes. The theoretical density of the vapour of chloride of tita- 
96 
Carr 6°648. 
This mode of calculating the vapour density presents several ad- 
vantages : it does not at all require the knowledge of the vapour 
densities of the elements of which a substance is composed. 
The formula of a compound is only taken into consideration in as 
far as it serves to fix and calculate its equivalent. This equivalent 
being known, the nature and number of the elements contained ina 
compound are of little consequence. The density of the vapour may 
be calculated independently of these data. 
With a great many substances, in fact, the vapour density is 
observed to depend entirely upon the weight of the equivalent. 
Thus caproic alcohol, C'? H'* O%, propionate of zthyle, C!° H'° O+, 
and anhydrous acetic acid, C* H® O°, which with very different for- 
mule have the same equivalent, 102, have also the same vapour den- 
sity, 3°332. Carbonic acid and protoxide of nitrogen have the same 
equivalent, 22, and the same density, 1524, Formic acid, C?H20+4, 
and alcohol, C+ H® O2, have the same equivalent, 46, and the same 
density of vapour, 1°592. Phenole, C'? H® O2, and bisulphuret of 
methyle, C+ H® S*, the composition of which is so different, have 
the same equivalent, 94, and the same density of vapour, 3°255. 
In general the vapour densities of substances which have the 
same equivalent are equal, or stand in very simple relations. It 
therefore appears rational only to take into consideration the equi- 
valent in calculating the vapour density.— Comptes Rendus, June 29, 
1857, p. 1347. 
ON THE FORMATION OF WATER BY PLATINUM ELECTRODES. 
BY M. BERTIN. 
Electricity, like heat, may give laminated platinum the property 
of producing the combination of hydrogen with oxygen either slowly 
or with explosion. 
When platinum plates have transmitted the current of at least 
forty elements into acidulated water, if they are covered by a bell- 
glass to collect the mixture of oxygen and hydrogen, this mixture 
detonates spontaneously as soon as the bell-glass is nearly full of gas. 
If the current be less energetic, the explosion of the mixture does 
not take place, but its slow recomposition maintains the volume 
of the gases constant, notwithstanding the incessant decomposition 
which takes place at the Jower part of the electrodes. 
nium is therefore 
