374 Miscellaneous Intelligence. 
Liquids, &c., by M. Becquerel.—The apparatus used by M. Beequerel 
to collect and indicate the electricity developed by the contact of a 
solid with a liquid is a condensing clectroscope of extreme sen- 
sibility, invented some time since by M. Bohnenberger*, but varied 
and rendered more delicate for the present purpose by M. Becquerel. 
The instrument of the latter philosopher consisted of a single dry 
voltaic column fixed horizontally on a wooden support, and having 
attached to each of its poles, in a vertical position, a plate of metal 
about 3 inches long: these plates are placed near together, and a 
slip of gold leaf hung between them, connected with a condensing 
plate 9 inches in diameter. The sensibility of this apparatus is such 
that a tube of glass rubbed on cloth acts in dry weather at a distance 
of 8 or 10 feet, and the electric state of the hand or hair has an 
influence at the distance of several fect. Hence the utmost precau- 
tion is requisite in experimenting with the instrument. 
The following are some of the experiments made with this appa- ° 
ratus, the gold leaf being in communication in all of them with 
the lower plate of the condenser. A brass capsule containing an 
alkaline solution, or ammonia, was placed on the upper plate of the 
condenser: a communication was then made with the solution by 
touching it with the finger, or a moistened band of cloth, and 
the lower plate was also connected with the earth; a few moments 
after the upper plate was raised, and the gold leaf moved towards 
the positive pole; thus the alkaline solution, or ammonia, by con- 
tact with the copper, had taken positive electricity, and the metal 
negative electricity. 
When sulphuric acid was used in place of alkali, opposite elec- 
trical effects were produced, the acid became negative, and the 
metal positive. 
A platina capsule filled with an alkaline solution was placed on the 
upper condensing plate ; the under plate was then touched on the one 
hand by a plate of platina, and on the other the liquid was touched 
by the finger, and in this manner the electro-motive actions of the 
platina on the copper was neutralized, being the same on both sides, 
and therefore the upper plate would only retain the electricity due 
to the contact of the platina with the solution. Sometimes it is ne- 
cessary to put a small piece of paper between the platina and the 
copper, for the apparatus is so sensible, that a very small difference 
in the state of the surfaces is sufficient to influence the results. Ope- 
rating thus the same results were obtained as before with alkali; the 
platina became negative, and with acid it became positive. A zinc 
capsule filled with solution of soda became negative, and with con- 
centrated sulphuric acid positive; when the acid was diluted no elec- 
tricity was developed. Silver became very feebly electrical in con- 
tact either with acid or alkali. 
* See vol. xi. p. 208, of this Journal. 
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