of Edinburgh, Session 1871-72. 
699 
4. On the Temperature of the Electric Spark. By 
James Dewar, Esq. 
(Abstract.) 
The author begins this paper by calculating the highest hypo- 
thetical temperature that could be produced by the chemical 
combination of the most energetic elements if all the heat evolved 
could be thrown into the product. This would not exceed 19,500° 
C. in the case of silica, and 15,000° O. in the oxides of aluminum and 
magnesium, and these are the highest results. The estimation of 
the temperature of the electric spark is based on the thermal value 
of each spark, together with the volume of the same. The 
methods of observing these quantities are fully detailed in the 
memoir. The general result may be stated thus, — the tempera- 
ture of the electric spark used in the experiments ranged between 
10,000° C. and 15,000° O. 
The following Gentlemen were admitted Fellows of the 
Society : — 
James Thomson Bottomley. 
Thomas Knox, Esq. 
Dr D. Argyll Robertson. 
Monday , \5th April 1872. 
Professor KELLAND, Vice-President, in the Chair. 
The following Communications were read : — ■ 
1. On the Action of Water on Lead. By Sir Bobert 
Christison, Bart. 
After summarising the conclusions at which he had arrived from 
numerous experiments made more than forty years ago, as published 
in his Treatise on Poisons, and in the Transactions of this Society, 
the author alluded to various blanks left at that time in the inquiry 
which had not been yet filled up, and to various criticisms and 
doubts which had been recently expressed relative to the facts and 
principles formerly announced. 
