976 REPORT—1885. 
11. Description of some new Orystallised Combinations of Copper, Zinc, and 
Tron Sulphates. By Joun Spitzer, F.C.S. 
It was known that these metallic sulphates were capable of crystallising 
together, but the author had made experiments with the view of getting definite 
combinations. 
In consequence of the wide differences in the degree of solubility, it was 
necessary to employ the zinc salt in large excess, so as to force this ingredient into 
the combination. Sulphate of copper being, on the other hand, much more 
sparingly soluble, had a tendency to separate out alone, or with at most 8 to 10 
per cent. of zinc (or iron) sulphate in admixture. 
A large series of well crystallised double salts had been prepared and analysed, 
of which the following were the most definite examples :— 
Cu Fe (SO,), +12 aq. 
Zn Fe,(SO,), +28 aq. 
‘Zn, Fe,(SO,), + 35 aq. 
Cu Zn,(SO,), + 26 aq. 
Cu Zn,(SO,), +58 aq. 
Cu Zn,(SO,), +40 aq. 
The last named double salt could be obtained in magnificent pale-blue rhombs, 
like a tinted calc-spar, but not double refracting. The tri-zinc cupric sulphate had 
long ago been prepared by Lefort, who asserted, Lowever, that it contained 28 
molecules of water, a statement which the author believed to be incorrect, finding 
by his analysis that each salt introduced its own proper amount of water of 
crystallisation, 
SATURDAY, SEPTEMBER 12. 
The following Papers were read :— 
1. The Composition of Water by Volume. 
By A. Scorr, M.A., D.Sc., F.R.S.E. 
No determinations as such of the ratio of the volumes in which oxygen and 
hydrogen combine to form water have been made since those of Humbeld and 
Gay-Lussac in 1805. The experiments of Regnault and Amagat show conclu- 
sively that neither of these gases obeys Boyle’s law, their deviations being in 
opposite directions ; hence if we admit Avogadro’s law for perfect gases, it could 
only be by the merest chance that the true ratio would be 2 of hydrogen to 1 of 
oxygen, With the improved methods for preparing and measuring gases now at 
our command, it seemed that this important ratio ought to be redetermined, if possible 
on a larger scale. The quantities operated on are about 150 c.c. of oxygen and 
300 c.c. of hydrogen in each case. Two experiments gave the following ratios— 
1: 1/994 
and 
1: 1:9935 
or 
1 : 1:9960 
if the impurity be supposed to exist in oxygen alone. 
The purity of the gases was tested by subsequent analysis, of the residue, and 
‘2 to 3.c.c. of foreign gas found in 450 c.c. of gas used. 
The author, however, hopes by his processes of preparing the gases to obtain 
them in a still higher degree of purity. 
