298 Mr. W. Sutherland on the Recalculation of 



measurements as a whole. For although it is likely that errors 

 may occur in some of the individual members, it is hardly 

 possible that the whole are erroneous. It will therefore fol- 

 low that undulations of a length of about one sixty-fourth of 

 an inch (taking the mean measurement) accompany the dis- 

 ruptive discharge. 



The photographs from which the figures in the Plate are 

 copied were taken for me by Mr. Dunscombe, of Bristol, and 

 were printed from the negatives without the latter being 

 touched in any way. 



Note, June 9, 1888. — Since the above was written, I have 

 been informed by Prof. Pucker that he has an apparatus in 

 his possession, made by the late Dr. Guthrie, which gives 

 somewhat similar results. This was copied from one exhibited 

 at the Loan Exhibition of Scientific Apparatus in 1879. It 

 consists of an elliptical dish with vertical walls. Sand is 

 scattered over the bottom, a glass plate placed over the top, 

 and a series of electric sparks produced at one focus of the 

 ellipse. The sand will then be found to arrange itself in a 

 series of circular curves around the other focus. The curves 

 thus produced bear a striking resemblance to those exhibited 

 in the Plate accompanying this paper, and are of course due to 

 the same cause. 



XXXII. On the Recalculation of certain Specific Heats at 

 High Temperatures, and the Specific Heat of Water. By 

 William Sutherland, M.A., B.Sc* 



IN the course of some work on molecular physics I was led 

 to search for some accurate measurements of the specific 

 heats of liquids at high temperatures, and found that, although 

 Hirn had conducted some good experiments, his results had 

 not been accepted on account of their disagreement with those 

 of Pegnault. Thus, while for the heat necessary to raise 

 ether from 0° to t Hirn gives the formula 



2 = -564£+ -000799 **— 5 268f + *0 7 181* 4 , 

 Pegnault gives 



q= -529 * + -000296 **. 

 For alcohol Hirn gives 



2=-4229* + -00274* 2 --0 4 132£ 3 + -0 7 506* 4 , 



while Regnaulfs formula is 



q = -5475 1 + -00112 1 2 + -0 5 221 1\ 

 The great differences between the values for the specific heats 

 * Communicated by the Author. 



