[ 345 ] 



XLVIII. On some Phcenomena of Heat. By R.W. Fox, Esq.* 



A LTHOUGH several years have now elapsed since I 

 ■^^ made a series of experiments on what is termed the 

 Radiation of Heat, I venture to hope that a brief statement 

 of some of the results may not be unacceptable to those who 

 take an interest in this subject. 



1 suspended by a thermometer in an exhausted glass re- 

 ceiver, a small cylindrical bright tin-plate vessel, of the capa- 

 city of about two cubic inches, containing hot sweet-oil, and 

 carefully noted its time of cooling. To avoid needless repe- 

 tition, 1 shall call this vessel of oil No. 1. 



The experiment was repeated with a similar vessel ex- 

 ternally coated with lamp-black. This vessel of oil I shall 

 call No. 2. 



They were afterwards each respectively inclosed in cylin- 

 drical tin-plate cases, f ths of an inch larger in diameter and 

 depth, so as to leave a space between them and the latter of 

 Y^^ths of an inch ; and in this position they were retained by a 

 small pin, fixed at the bottom of each, and penetrating the 

 cases. When more cases than one were used, the intervals 

 between them were also at least y^^ths of an inch. 



The glass receiver I employed was 3|ths inches in diame- 

 ter, and it was enveloped with damp linen, at the temperature 

 of 60°, and the air exhausted to nearly j^^th part. The fol- 

 lowing Table shows the times of cooling from 220° to 170° 

 {i.e. from an excess of 160° to 110°) ; and in order to insure 

 the regular diffusion of the heat, the oil was poured into the 

 vessels Nos. 1. and 2. at the temperature of 320° to S^O". 



Most of the experiments were repeated in air confined under 

 the receiver, and the results are given in the second column. 



* Conuiumicated hv the Author. 

 N.S. Vol. 1 1. No. 6,^. Mdij 1832. 2 Y 



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