193 



also wliy the only other person who I believe has attempted to ob- 

 tain tliem was led to the opposite conclusion, as stated by M. Mel- 

 loni in the Annales dc Chimie for May 1837, namely, that all kinds 

 of heat are equally susceptible of polarization. I have at length 

 discovered, in the description of M. Melloni's method, the cause of 

 his failure to detect this fact. 



" 2. I have ascertained the laws and measures of the depolariza- 

 tion of heat by the doubly refractive energy of mica plates, by three 

 series of experiments with heat from different sources, each per- 

 formed with mica of various thicknesses. 



" 3. I have discovered a method of measuring the mean index of 

 refraction of heat from different sources with very considerable 

 numerical exactness, which it is believed is now done for the first 

 time ; and the results confirm the opinion already entertained, that 

 dark heat is the least refrangible, whilst that portion of luminous 

 heat which is transmitted by glass is the most refrangible. The 

 principle of the method includes a complete analysis of the hetero- 

 geneous heat derived from any source into any number of portions, 

 between assigned limits of refrangibility." 



Monday, 5th March. 

 Sir T. M. BRISBANE, Bart. P. in the Chair. 



The following Honorary Fellows were elected : 

 Prof. Tiedemann, Heidelberg. 

 Prof. Miiller, Gottingeu. 



The following Donations were presented : 



Elements of Chemistry, by the late Edward Turner, M. D., sixth 

 edition, enlarged and revised by Professor Liebig and Wilton 

 G. Turner. Part 1 1 . — By the Editors. 



Comptes Rendus Hebdomadaires des Seances de I'Acaderaie des 

 Sciences. No. 6, 1" Semestre 1838 By the Academy. 



Flora Batava. Nos. 1 12 and 113 By tlie King of Holland. 



On the Nature and Treatment of the Diseases of the Heart ; with 

 some views on the Physiology of the Circulation. By James 

 Wardrop, M. D., Surgeon to his late Majesty Geo. IV., &c. &c. 

 By the Author. 



Notice sur les Marbres ; par M. Theodore Virlet By the Autluyr. 



The Quarterly Journal of Agriculture, and the Prize Essays and 

 Transactions of the Highland and Agricultural Society of 

 Scotland. No. 40, March 1888 By the Society. 



