206 ) 



jwr 



On a New Electrometer, and the Heat excited in Metallic Bodies 

 by Voltaic Electricity. By WILLIAM SNOW HARRIS, Esq. 

 F.R.S. 



(Read December 19. 1831.) 



1. J.N the course of some inquiries concerning the power of me- 

 tallic substances to conduct intense electrical explosions, an ac- 

 count of which was honoured by a place in the Philosophical 

 Transactions for the year 1 827, 1 sought to obtain a comparative 

 measure of the conducting power, in the heat evolved by the 

 metal, at the time of transmitting the charge. The instrument 

 employed for this purpose, was, in principle, that of a common air 

 thermometer, the given metal, the subject of experiment, being 

 drawn into a wire, and passed air-tight across its bulb. This 

 simple contrivance, I have since extended to the general purposes 

 of an electrometer, so as to estimate the force of any ordinary 

 electrical accumulation. The results arrived at with voltaic 

 combinations, seem, for the most part, of much practical utility ; 

 and therefore some account of them may, I trust, be found wor- 

 thy of the attention of the Royal Society of Edinburgh. 



2. The electrometer, as prepared for the purposes of voltaic 

 electricity, will be easily understood by the following descrip- 

 tion : abc, Fig. 1, Plate VIII., is a fine glass-tube, whose interior 

 diameter is about the T Vth o f an inch ; there is a spherical reser- 

 voir blown at a for the reception of a coloured fluid ; from this 



