222 Messrs. Rosa and Smith on a Calorimetr 



IG 



sible that the resistance might not tend to vanish, but, as in 

 the case apparently of bismuth, might increase with further 

 fall of temperature. It has been suggested that at very low 

 temperatures all metals might become magnetic. It is very 

 probable that the change of electrical structure here indicated 

 would be accompanied by remarkable changes in the magnetic 

 properties. These are some of the points which experiment 

 will probably decide in the near future. The only experi- 

 mental verification at present available is the observation of 

 Dewar in the case of platinum No. 3 when immersed in 

 boiling hydrogen at —240° C, that the resistance after at- 

 taining a very low value apparently refused to diminish 

 further, in spite of a considerable lowering of the pressure. 

 It would be extremely interesting to repeat this observation 

 with specially constructed thermometers of copper or iron, 

 which ought to show the effect in a more striking manner 

 and at a higher temperature. 



My thanks are due to Messrs. E. H. Griffiths, C. T. Hey- 

 cock, and F. H. Neville, and to Prof. A. W. Porter and 

 Mr. N. Eumorfopoulos, for their kind assistance in revising 

 and correcting the proofs of this article. 



X1Y. A Calorimetric Determination of Energy Dissipated in 

 Condensers. By Edward B. Rosa and Arthur W. Smith*. 



IN a former paper {supra, p. 19} we gave the results of mea- 

 surements by means of a wattmeter of the energy dissipated 

 in condensers when they were subjected to an alternating 

 electromotive force. The results were such that we desired 

 to confirm them by a totally independent method : and, in 

 addition, to measure the energy dissipated in some paraffined- 

 paper condensers which showed so small a loss that with the 

 coils at our disposal the Resonance Method, employed success- 

 fully on beeswax and rosin condensers, would not give 

 sufficiently accurate values. We therefore constructed a 

 special calorimeter for the purpose of measuring the total 

 quantity of heat produced in the condensers, which represents 

 the total energy dissipated. 



Fig. 1 gives an external view of the calorimeter, and fig. 2 

 a vertical section. The calorimeter proper, A, is the inner of 

 three concentric boxes, and is 33 cm. long, 30 cm. deep, and 

 10 cm. in breadth. It has a copper lining, a, and a copper 

 jacket, b, and is protected by the two exterior boxes from 

 fluctuations of temperature without. The general principle 

 of the calorimeter is (1) to prevent any loss or gain of heat 

 * Communicated by the Authors. 



