458 Royal Society :-— 
The electromotive force which is developed when a certain pres- 
sure forces pure water through a clay plate, is independent of the 
size and thickness of the plate, and also of the amount of water 
that has flowed through, but is proportional to the pressure em- 
ployed. 
The multipliers used for these experiments were such as are 
employed by M. E. du Bois-Reymond in his researches in organic 
electricity. In one of the instruments the wire was wound no 
less than 33,000 times round the frame, in the others 10,080 
and 600 respectively. 
In a subsequent Number of Poggendorff’s Annalen (Part 11 
for 1859), M. Quincke announces that he has since discovered 
that, by using flowers of sulphur as a porous diaphragm, the 
electromotive force, all other circumstances remaining equal, is 
incomparably greater ; and that this substance is therefore better 
suited than burnt clay for forming a diaphragm-apparatus, so 
that now there will be no further difficulty in demonstrating 
these electrical currents under moderate pressures. The sulphur 
which was mentioned in the original paper as being used for a 
porous plate, was roll-sulphur ground to powder in an agate 
mortar, as were also the tale and the graphite. At the close of 
his supplementary notice, M. Quincke remarks that he has been 
able to establish the two following facts with respect to these 
electrical currents; first, that they produce chemical decomposi- 
tion; and secondly, that they afford evidence of free electricity. 
LXIII. Proceedings of Learned Societies. 
ROYAL SOCIETY. 
[Continued from p. 398. ] 
Dec. 8, 1859.—Sir Benjamin C. Brodie, Bart., Pres., in the Chair. 
f es following communications were read :-— 
“Supplement to a Paper ‘On the Influence of White Light, of 
the different Coloured Rays, and of Darkness, on the Development, 
Growth, and Nutrition of Animals*. By Horace Dobell, M.D. &c. 
The apparatus used in the following experiments, was described in 
my Paper; but in the present instance, only two of the cells were 
employed, viz. that exposed to ordinary white light, and that from 
which all light is excluded. In order more effectually to prevent 
the possible admission of light, the following precautions were adopted 
with the dark cell:—1. The perforated zinc floor was covered with 
thick brown paper. 2. The under surface of the lid was lined with 
black cloth, to secure accurate adjustment when shut, 3. The 
opaque black glass was covered with an additional coat of black oil- 
paint. 4. The lid was never opened in any light except that of a 
candle or of gas. ; 
* Phil. Mag. S. 4. vol. xviii. p. 143. 
