32 ; REPORT—1874. 
being the result. Carbon disulphide may also be added to the oils, or acted on 
alone. Other conducting liquids, not miscible with ether, may also be used as 
anodes or cathodes. 
Oils, however, which are not soluble in alcohol are only partially soluble in the 
ferric ether, which fact also suggests matter for future experiments, The author 
considers it a significant fact that in some of these experiments carbon disulphide 
was evidently decomposed, either directly or indirectly, by the current, although he 
has not yet succeeded in getting a deposit of carbon. 
A cheap and convenient Galvanic Battery adapted for weak but continuous 
Currents. By W. Symons, F.C.S. 
This home-made battery, adapted either for a water-battery or for a weak saline 
solution, was used in the previous experiments, and is also described in the 
‘ Pharmaceutical Journal’ for October 1874. 
On the Effect on the Compass of the Rolling of Ships*. 
By Sir W. Tuouson, F.RS. 
On the Proportions in which Bases and Acids present in a Solution combine with 
each other. By Professor Gustay WIEDEMANN, Leipzig University. 
When a base is introduced into a solution containing two different acids, it is 
divided between them ; likewise, when salts are dissolved in water, they very often 
undergo a partial decomposition. Thus, for example, the salts of iron peroxide 
dissolved in water are partially decomposed into acid, and colloid peroxide of iron 
remaining in solution. 
The author has applied to the investigation of this phenomenon a method pre- 
viously employed by him for the determination of the magnetism of chemical com- 
pounds. In this process the effect which is to be determined is not measured 
during the continuance of the chemical action, as is customary in measuring calo- 
rific effects, but after the complete termination of the action, and without the inter- 
vention of any external agent, physical or chemical. 
This method has as its basis the difference which exists between the magnetism 
of the colloidal peroxide of iron and that of the peroxide contained in the salts. 
When in a solution of a neutral or feebly acid salt of peroxide of iron a portion of 
the salt is decomposed into free acid and colloid peroxide in solution, the modifi- 
cation which the magnetism undergoes should enable us to calculate the quantity of 
salt decomposed. 
If we designate by m, the magnetism in a unit of weight of iron in its ferric salts 
in a solid state or dissolved in an excess of acid, by m, the magnetism of a unit of 
weight of iron contained in the colloid peroxide in solution, by m the magnetism 
of the unit of weight of iron in any solution whatever of a salt of iron peroxide 
which has undergone a partial decomposition, and, finally, by 1—2 : x the ratio of 
the quantity of the peroxide remaining combined in the form of salt to the quantity 
of the peroxide that has assumed the colloid state, we have 
m=m,(1—x)-+m,2, 
and consequently 
__m,—m 
x : 
My — My 
The ratio 1 : « is thus immediately deduced from the measure of the magnetism 
of the solution. In this way the following results have been obtained :— 
1. The magnetism of a solution of ferric sulphate does not undergo any sensible 
change, even when so diluted as to reduce the quantity of iron contained in 10 
cubic centims. of the solution from 0°57 gramme to 0:07 gramme. 
* Published in ‘Nature,’ vol. x. p. 338 (Sept. 10, 1874). 
