﻿20 Messrs. E. T. Chapman and M. H. Smith on the 



By pointing the needles, or giving them the rhomboidal form, 

 it is evident that, in spite of the poles being nearer (as is well 

 ascertained to be the case in needles of that shape), the ratio of 

 the magnetic moment to the moment of inertia is still higher than 

 in the assemblage of oblong needles. Though, for various 

 reasons, the rhomboid set on its edge is scarcely ever used in 

 practice, an easy calculation shows that it is the most perfect 

 form for a moveable magnet. It seems only to have been tried 

 when lying flat. 



Seymour Chambers, Adelphi, W.C. 

 London, November 20, 1868. 



III. Action of Dehydrating Agents on Organic Bodies. 

 By E. Theophron Chapman and Miles H. Smith*. 



CANE-SUGAR, as is well known, yields carbon on treatment 

 with strong sulphuric acid, which removes the elements 

 of water. In like manner strong sulphuric acid dehydrates 

 common alcohol, yielding olefiant gas. Chloride of zinc removes 

 water from amylic alcohol, yielding amylene. Anhydrous phos- 

 phoric acid converts acetate of ammonia into acetamide, and 

 finally into cyanide of methyle. All these are well-known and 

 characteristic examples of the violent dehydration of organic 

 substances. The three short notices which follow describe fresh 

 cases of the action of dehydrating agents. 



The first is the instance of nitrate of amyle with phos- 

 phoric acid : there is very violent dehydration, and pyridine is 

 produced, 



C 5 H ]1 N0 3 -3H 2 = C 5 H 5 N. 



The second is the dehydration of formiate of amylamine by 

 means of chloride of zinc : there is produced wo-cyanide of amyle, 



CH 2 O 2 N C 5 H 13 -2H 2 = C N C 5 H 11 . 



The third is a case in which a strong dehydrating agent refused 

 to perform a violent dehydration, viz. the action of chloride of 

 zinc on oxalate of amyle. The equation 



C 2 4 (C 5 H n ) 2 -4H 2 = C 12 H 14 

 was not realized. 



That which actually did happen was as follows : — 

 C 2 4 (C 6 H 11 ) 2 -H 2 = C 2 3 + 2(C 6 H 10 ). 



I. On the Artificial Production of Pyridine. 



Pyridine has been produced by Perkin from azo-dinaphthyl- 

 diamine (C 20 H 15 N 3 ) by the action of nascent hydrogen. This 



* Communicated bv the Authors. 



