160 Intelligence and Miscellaneous Articles. 



Table L — Impulsion Method. 



Temperatures measured by the 

 actinometer. 



Intervals. , * N 



, *=10. *=8-2. t = 7-2. t=32. 



-L 24 toO 16 0-088 0-042 0-031 0-0 



16 „ 1 36 0-443 0-441 0-433 0-307 



1 36 „ 2 56 0-404 0-419 0-435 0-528 



2 56 „ 4 16 0-064 Q-Q98 0-101 (KL64: 



(>999 1-000 1-000 (F999 

 Platinum begins to melt when the actinometer gives 10-3. 

 Taking the ratios of the quantities of heat measured by the pile 



to those measured by the actinometer, we have for the temperatures 



10, 8-2, 7-2, 3-2, the ratios 9-14, 5-86, 5-77, 4-38. 



Table II. — Fixed-temperature Method. 



Temperatures measured by the actinometer. 



Intervals. • ■ * v 



; 9o. 74. 60. 4-6. 40. 



-044to016 0-056 0-052 0-045 0-024 0-024 



16 „ 1 36 0-445 0-420 0-406 0-394 0-388 



1 36 „ 2 56 0-400 0-427 0-433 0-464 0*453 



2 56 „ 4 16 0-098 0-100 0-114 0-116 0-134 



0-999 0-999 (^998 0-998 0-999 



If we take the ratios of the quantities of heat spread over the 

 luminous part to the total quantities diffused throughout the 

 spectrum, we have for the foregoing temperatures the numbers 

 0-030, 0-022, 0-012, 0-003, 0. 



Taking, as before, the ratios of the quantities of heat indicated 

 by the pile to those indicated by the actinometer, we have the 

 numbers 7*09, 5-74, 5-53, 5-24, 5-02. 



Tables I. and II. show the variations of the distribution of heat 

 in the spectrum with the temperature ; and from them we infer that 

 flint glass becomes less diathermanous as the temperature falls. 



Finally, by interposing in the path of the radiation from the source 

 a solution of iodine in chloroform, I found that the minima, the 

 existence of which we had previously recognized, all undergo paral- 

 lel displacements proportional to the fall of the temperature. This 

 assertion is verified by the following Table. 



Minima. 



Temperatures. a. b. c. 



9-8 1 20 to 1 24 I 40 to 1° 44 2 to 2° 4 



9-5 1 24 to 1 28 1 44 to 1 48 2 4 to 2 8 



4-5 1 40 to 1 44 2 20 to 2 24 



4-0 1 44 to 1 48 2 4 to 2 8 2 24 to 2 28 



3-8 1 48 to 1 52 2 28 to 2 32 



I also noticed that the above solution becomes more diatherma- 

 nous when the temperature is lowered. 



I am studying the spectra of other substances, and, in speaking 

 of them, shall return to the last -mentioned subject. — Comptes 

 Rendus de VAcademie cles Sciences, vol. lxxxii. pp. 1153-1156. 



