$SS Royal Institution :—Mv , Grove on Voltaic Reaction, 
bismuth to silver ; or if the hydro-sulphuret of potash be used, it is 
from bisinuth to silver, and from silver to antimony ; and, finally, 
if strong muriatic acid be used, it is precisely the reverse, or from 
antimony to silver, and from silver to bismuth. The inconsistency 
of these results with the contact theory is then insisted on and 
further developed. 
The last section of this series is on the improbability of there ex- 
isting any such force as the assumed contact force. The author 
contends that it is against all natural analogy and probability that 
two particles which, being placed in contact, have by their mutual 
action acquired opposite electrical states, should be able to discharge 
these states one to the other, and yet remain in the state they were 
in at the first, i. e., entirely unchanged in every point by what has 
previously taken place ; or, that the force w'hrch has enabled two 
particles by their mutual action to attain a certain state, should 
not be suflftcient to make them keep that state. To admit such ef- 
fects would be, he thinks, to deny that action and reaction are 
equal. The contact theory, according to him, assumes that a force 
which is able to overcome powerful resistance, both chemical and 
mechanical, can arise out of nothing. That without any change in 
the acting matter, or the consumption of any other force, an electric 
current can be produced which shall go on for ever against a con- 
stant resistance, or only be stopped, as in the voltaic trough, by the 
ruins which its exertion has heaped in its own course ; — this, the 
author thinks, would be a creation of power, such as there is no 
example of in nature ; and, as there is no difficulty in converting 
electrical into mechanical force through the agency of magnetism, 
would, if true, supply us at once with a perpetual motion. Such a 
conclusion he considers as a strong and sufficient proof that the 
theory of contact is founded in error. 
FRIDAY-EVENING MEETINGS AT THE ROYAL INSTITUTION^ 
January 24, 1840. — Mr. Faraday on voltaic precipitations. 
January 31. — Dr. Grant on the structure and growth of corals. 
February 7. — Mr. Faraday on a particular relation (Dove’s) of 
condensable gases and steam. 
February 14. — Mr. Gatlin’s account of his residence and adven- 
tures among the native tribes of North America, with notices of 
their social condition, customs, mysteries, mode of warfare, tortures, 
&c. 
February 21. — Mr. Nasmyth on the origin of alphabetic charac- 
ters, and on the pneumatic mirror. 
February 28. — Mr. Brayley on the application of science to the 
choice of building stones, with reference to the selection of stone 
for the New Houses of Parliament. 
March 6. — The Rev. Mr. Hincks on the monstrosities of plants. 
March 13. — Mr. Grove on voltaic reaction, or the phenomena 
usually called polarization. 
Mr. Grove detailed the first experiments of Volta, Erman, Ritter, 
and Davy, the more recent ones of De la Rive, the explanation of 
these by Becquerel, and the confirmation of this latter philosopher’s 
