Radiant Heat, and its Conversion thereby into Sound. 447 



vestigation on the power of gases to conduct heat*. His 

 apparatus, traced in outline from his own plate, is shown in 

 fig. 1, where A B is the recipient for the gases, and C a flask 

 containing water kept boiling by a current of steam. The 

 bottom of C, which 



formed the top of A B, Fig-. 1. 



was the source of heat. 

 A thermometer, g f, 

 shielded by a oork or 

 metal screen o o' from 

 the radiation of the 

 source, was intended 

 to receive and measure 

 the heat transmitted 

 by conduction. The 

 recipient A B was 

 mounted in a space 

 surrounded by water 

 of a constant tempe- 

 rature. The heating 

 of the thermometer 

 when A B was ex- 

 hausted t, was com- 

 pared with its heating 

 when A B was filled 

 with various gases ; 

 and in every case 

 but one the heating 

 through the gas was 

 found less than the 

 heating through the vacuum. The exception was hydrogen, 

 which carried more heat to the thermometer than was trans- 

 mitted by the vacuum. The conclusion drawn by its author 

 from this experiment was that hydrogen conducted heat like 

 a metal. 



One remark only in this Note has any reference to the 

 diathermancy of gases; but it is a significant one. Magnus 

 had no doubt as to the power of every one of his gases to 

 conduct heat. There could, he supposed, be only a difference 

 of degree between them and hydrogen. Whence, then, the 



* A Preliminary Note of this inquiry is published in the Bericht of 

 the Berlin Academy for July 80, 1860. No measurements are given ; 

 but certain results are announced. The experiments were first published 

 in Poggendorff s Annalen for April 1861. 



t This vacuum-temperature, at least in so far as it exceeded that of 

 the sides of the recipient, was obviously derived from the screen. 

 2L2 



