214 Dr. Anderson on the Products of the 



is equivalent to 



or 



idx+jdy = dp; 

 whence 



ix+jy-p + a., 



a. being an arbitrary vector ; or, between given limits, 



*(a? s -a?,) +>(yt— yO =P2-P\> 

 an identity, as it ougbt to be. 

 Similarly, the second equation 



(kP+ehf+dz*:*^ 

 is equivalent to 



- {idx +jdy + kdz)-= - {dp) 2 , 

 or 



idx +jdy + Mz = dp ; 

 whence 



a being an arbritrary vector, or, between given limits, 

 i{x^-x x ) +j(y2—y x )+k(z i —Zi)—p i —pv 



an identity, as it ought to be. 



5 Trinity College, Dublin, 

 November 1854. 



XXXI. On the Products of the Destructive Distillation of Animal 

 Substances. — Part III. By Thomas Anderson, M.D., Regius 

 Professor of Chemistry in the University of Glasgoiv. 

 [Concluded from p. 150.] 

 Constitution of the Bases of the Picoline Series. 



HAVING in this and the previous part of these researches 

 accumulated sufficient evidence of the existence of a class of 

 bases isomeric with that of which aniline is the type, it became 

 important to determine to which of the three classes of volatile 

 bases they belong. For this purpose, pyridine, picoline, and 

 collidine were submitted to the action of iodide of sethyle. The 

 experiments were carried out in considerable detail with picoline, 

 but with the other two salts no more was done than sufficed to 

 substantiate the fact, that iodide of sethyle acted on them in a 

 similar manner. 



Action of Iodide of JEthyle on Picoline. 



Anhydrous picoline and iodide of sethyle were mixed, in the 

 proportion of one volume of the former to two of the latter, and 



