A SYSTEM OF PARTICLES. 281 



In fact V- now takes the form 



QA being the coefficient of b^ sin'' above. 



A 



48. Of course, I do not mean to offer this as a solution of the 

 equation, but merely as a proof of the possibility of its taking the 

 above form : the quantity A may, in fact, be very different indeed 

 from that above exhibited. 



49. Now we found in the case of the ten substances examined 



by Fraunhofer, that eight of them gave the coefficient - negative, 



whilst the other two gave it positive; the value of AU must then be 

 considerable (supposing the explanation of the fact to be contained 

 here), and greater in the cases of glass than of water. 



Now }f, in the view above given, will determine the quantity of 

 heat transmitted with the spectrum under any given circumstances, it 

 follows therefore that substances which transmit heat most freely give 

 / small, and hence referring to the list in my former paper, I obtain 

 the following order for transmission of Heat, beginning at that in 

 which the freedom of transmission is the greatest. 



Flint Glass, No. 30. \ 

 23.f 



13. 



Oil of Turpentine. 



Crown Glass, Let. M. 

 No. 13. 



3.; 



Water. 

 Solution of Potash 



i 



