64 



heat converted into expansive power to the total quantity received 

 by the body, is equal to that of the difference between the tempera- 

 tures of reception and emission, to the absolute temperature of re- 

 ception diminished by a certain constant denoted by r. = C « /. f> 

 in the paper; which constant must be the same for all substances 

 in nature, in order that molecular equilibrium may be possible. 1 hat 

 is to say, let r, be the absolute temperature at which heat is received, 

 and r that at which it is emitted ; then 



maximum of Ji^eat^nsfoi^edjnto power^ ^ r^ - r„ 

 total heat received rj — x 



The value of x is as yet unknown, but as an approximation it 

 n..y be treated as small enough to be neglected in comparison 



"' Allhough this formula is very diflPerent from Professor Thomson's 

 iu appearance, the numerical results are nearly the same. 



The conditions of working to which Carnot's law is stnctly appli- 

 cable are not attainable in the steam-engine, and are different trom 

 those on which the author's formula, and tables in the fourth section 

 are based. The proportion of heat converted into power in the 

 steam-en.ine is therefore found, both by experiment and by calcula- 

 tion, to be less than that indicated by Carnot's law. The author 

 illustrates this fact by examples, theoretical and experimental. 



2 On the Products of the Destructive Distillation of Animal 

 Substances. Part II. By Dr Anderson. 



The author commenced by referring to the first part of his paper 

 in which he had determined the existence, among the products ot 

 destructive distillation of animal substances, of picoline, which he had 

 before obtained from coal-tar, and of a new base to which he had 

 given the name of Petinine ; and had also indicated the existence of 

 certain other bases. On proceeding to the further investigation 

 of these substances, he had been much impeded by deficiency in 

 materials, and had, at length, been compelled to operate on no less 

 than 250 gallons, or about a ton of bone oil. 



By separating the bases in a manner similar to that employed in 

 bis first experiments, but with some modifications detailed in the 



