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IX. An account of Experiments made with the view of ascertaining the 'possibility of ob- 
taining a Spark before the Circuit of the Voltaic Battery is completed. By John P. 
Gassiot, Esq. Communicated by P. M. Roget, 31.1). Sec. R.S. 8$c. 
Received October 11, — Read December 19, 1839. 
i. In presenting an account of the following experiments to the notice of the Royal 
Society, I am fully aware that the results are somewhat at variance with those ob- 
tained by philosophers whose names are so eminent in science, that it may appear 
presumptuous in me even to offer an opinion as to the correctness of their statements. 
The discrepancy may very possibly arise from error on my part ; but as the experi- 
ments relate to facts and not opinions, I can only state that I present a faithful 
record of those performed by myself with the assistance of two or three private friends, 
and that this record is extracted from my note-book, wherein the experiments were 
entered from day to day as they were performed. 
2. Until some recent experiments of Dr. Jacobi* no one appears to have disputed 
the correctness of Dr. Faraday’s original experiment of a spark appearing before con- 
tact, or before the circuit of a voltaic battery was completed, when consisting of a 
single pair of plates. 
3. That a spark does appear when the contact is made on completing the circuit of 
the voltaic battery, is well known to all who have experimented with that apparatus. 
Dr. Faraday has shown that this spark can be produced even with a single pair of 
plates-^; and although, in the preface affixed to the octavo edition of his Researches, 
this philosopher considers, from the results obtained by Dr. Jacobi, he was in error 
as to the spark taking place before contact, yet, with the precaution which he has 
described, the spark will invariably appear whenever the circuit is completed. 
4. Sir Humphry Davy, in his Elements of Chemistry^, says a bright spark was pro- 
duced of s^th or ^th of an inch in the open air, and in vacuo nearly half an inch, by 
using 2000 of Dr. Wollaston’s plates. 
5. Mr. Children informed us, that with 1250 pairs the spark was capable of pass- 
ing through a distance of ^th of an inch§. 
6. Dr. Henry, in his Elements of Chemistry, expressly states that the galvanic fluid 
passes through air and certain non-conductors in the form of sparks. 
7. In the edition of Turner’s Chemistry, now in the progress of publication, it is 
stated || that, on approximating the wires of an active circle, a brilliant spark passed 
between them just before contact, as well as in the act of breaking contact. 
* Philosophical Magazine, December, 1838, p. 401. t Philosophical Transactions, 1S34, § 957. 
+ Page 152. § Philosophical Transactions, 1809. || Page 153. 
