394 [Jan. 15, 



my laboratory by Dr. P. W. Hofmann. These two compounds 

 stand in the same relation to each other as ethylamine and ethylene- 

 diamine, as phenylamine and phenylene-diamine : 



Cl2 5 9 1 XT Benzidine- ( C vr 



Martylamme H N; M ^ iylene _^ lie 



-ti J EL 2 



This is not merely a relationship existing on paper ; whoever has 

 had these compounds in his hand will at once recognize the necessity 

 of placing them side by side ; but I may be allowed to point more 

 particularly to the remarkable similarity of the deportment of benzi- 

 dine under the influence of iodide of ethyl, this base exhibiting the 

 same reluctance to pass from the state of tertiary substitution to the 

 state of ammonium base a passage which, in the case of benzidine, 

 exactly as in the case of martylamine, had to be accomplished by 

 means of iodide of methyl. 



II. "On the Form of Crystals of Peroxide of Benzoyl." By 

 WILLIAM HALLOWS MILLER, M.A., For. Sec. R.S., Pro- 

 fessor of Mineralogy in the University of Cambridge. 

 Received December 18, 1862. 



The peroxide of benzoyl, C u H 10 O 4 , or carbon 69*42, hydrogen 

 4*13, oxygen 26'45, was discovered by Professor (now Sir B. C.) 

 Brodie, and described by him in the * Proceedings ' of the Royal 

 Society, vol. ix. p. 361. The crystals were obtained from a solu- 

 tion in ether of the product of the mutual decomposition of equi- 

 valent proportions of chloride of benzoyl and peroxide of barium 

 mixed in water. The faces of the crystals, though brilliant, were 

 not very even, so that, in order to obtain a moderately accurate 

 result, it was necessary to measure a large number of crystals. The 

 column headed ' observation J contains the means of the observed 

 angles ; the column headed * calculation, 5 the most probable values 

 of the angles, taking into account the quality of the faces containing 

 them, and the number of the observations in each case. 



System prismatic : 



101,001 =33 24' ; 1 1 0, 1 0=57 50'-5. 



