Intelligence and Miscellaneous Articles. 339 
opinion by the experiments of Dr. Schoenbein, Mr. Matteucci, and 
Mr. Grove himself; all which, as well as the experiments of Mr. Grove 
on the inactivity of amalgamated zinc, which he proved to be due to 
the same order of causes, have been already given in full in various 
numbers of the Philosophical Magazine. All the effects which have 
generally been included under the term polarization were proved by 
Mr. Grove to be traceable to one principle, viz. the electrolytic 
transfer of elements having for each other a chemical affinity, and 
the reaction caused by this affinity when the decomposing and trans- 
ferring power, i. e. the initial voltaic current, is arrested. What we 
are most anxious to call the attention of our readers to, are the asto- 
nishing effects exhibited by Mr. Grove at the conclusion of his lec- 
ture. Two batteries, little differing in construction from that de- 
scribed by him in the Lond. and Edinb. Phil. Mag., were charged 
some time previously to the lecture, and up to the period of its 
conclusion remained in perfect inactivity until the circuit was com- 
pleted. One of these was arranged as a series of five plates, and 
contained altogether about four square feet of platina foil ; with 
this the mixed gases were liberated from water at the surprising 
rate of one hundred and ten cubic inches per minute. A sheet of 
platinum, one inch wide by tw^elve long, was heated in the open 
air through its whole extent, and the usual class of effects pro- 
duced in corresponding proportion. With the other arrangement, 
consisting of fifty plates of two inches by four, arranged in single 
series, a voluminous flame of one inch and a quarter long was ex- 
hibited by charcoal points, which showed beautifully the magnetic 
properties of the voltaic arc, as Dr. Faraday held a piece of iron 
near it, being attracted and repelled by different portions of the 
iron : bars of different metals were instantly run into globules and 
dissipated in oxide. It should be borne in mind that all these effects 
were produced by a battery which did not cover a space of sixteen 
inches square, and was only four inches high, and which had been 
charged for some hours. 
Mr. Grove adverted to the letter of Prof. Jacobi to Dr. Faraday 
published in Lond. and Edinb, Phil. Mag., vol. xv. p. 161 , and stated 
that Mr. Pattison, who navigated the Neva with Prof. Jacobi in Octo- 
ber last, had observed that the batteries employed were on Mr. Grove s 
construction, which the Professor without hesitation admitted. 
March 20. — Mr. Schomburgk on the aborigines of Guiana. 
March 27. — Dr. Gregory on the statistics of disease and mortality 
in London. 
LVI, Intelligence and Miscellaneous Articles. 
THEORY OF SUBSTITUTIONS. POND GAS. 
M PERSOZ sent a letter to the Academy of Sciences, relating to 
• the conversion of acetic acid into pond gas and to the theory 
of substitutions. The author appears to have written, lest some ex- 
pressions made use of by M. Dumas, in the sitting of the 13th of Ja- 
nuary, should create a belief that he had entertained the same views 
as M. Dumas in arriving at the discovery of the production of pond 
