Royal Society. 385 



able ; for, except in larger treatises especially devoted to the subject, 

 the student will nowhere find the first principles of this beautiful 

 and powerful method so clearly and satisfactorily explained. The 

 only suggestion that occurs to us with respect to these chapters is 

 that they might be transferred with advantage to future editions of 

 the author's Treatise on Algebra ; for experiment has long since con- 

 vinced us that the method of determinants may be introduced with 

 great profit even in schools, and as soon as simple equations invol- 

 ving two or more unknown quantities are studied. We have found 

 that pupils of average intelligence rapidly acquire a knowledge of 

 the more elementary properties of determinants, and that they inva- 

 riably regard the method as a welcome augmentation of their com- 

 puting power. More important than this, however, is the fact that, 

 as a mental discipline, the study of the properties in question is cer- 

 tainly not inferior to that of any other branch of algebra. 



In heartily recommending the work, we will merely add that it 

 is enriched by a collection of well-chosen examples. 



LI. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



[Continued from p. 324.] 



November 22, 1860. — Major-General Sabine, R.A., Treasurer and 

 Vice-President, in the Chair. 



a^HE following communications were read : — 

 " Researches on the Phosphorus-Bases." No. X. — Metamor- 

 phoses of Bromide of Bromethylated Triethylphosphonium. By A. 

 W. Hofmann, LL.D., F.R.S. Received July 24, 1860. 



Among the several products of transformation into which the bro- 

 mide of bromethyl-triethylphosphonium is converted when submitted 

 to the action of reagents, the substances formed by its union with 

 bodies similar to ammonia, have hitherto almost exclusively occupied 

 my attention. I have, however, of late examined a variety of other 

 changes of this body, which deserve to be noticed. 



When heated, the bromide begins to evolve hydrobromic acid at a 

 temperature of about 200°, which continues for a considerable length 

 of time. The product of this reaction is evidently the bromide of 

 vinyl-triethylphosphonium, 



[(C 2 H 4 Br)(C 2 H 3 ) 3 P] Br=H Br 4- [(C a H 3 ) (C 2 H 5 ) 3 P] Br. 

 It is, however, difficult to obtain the substance pure by this process, 

 since the temperature at which the last portion of hydrobromic acid 

 is eliminated closely approximates the degree of heat at which the 

 vinyl-body is entirely destroyed ; and since the latter compound may 

 be obtained with the greatest facility by other processes *, I have 

 not followed up any further this direction of the inquiry. 



* The hydrated di-oxide of ethylene-hexetbyl-diphosphonium,when submitted 

 to distillation, undergoes decomposition; two different phases are to be distin- 

 guished in this metamorphosis. At about 200° the base begins to disengage the 



