On the Peroxides of the Radicals of the Organic Acids. 469 



We verify this by comparing the conducting-power of a pure 

 metal directly determined, with the conducting-power of the same 

 metal deduced from a determination of the conducting-power of its 

 alloy with small quantities of other metals. It is a curious fact, 

 that the deduced values from experiments upon hard-drawn wires 

 are in reality the conducting-powers of the annealed wire of the pure 

 metal. After having thus verified the method, we have not hesitated 

 to employ it in the determination of the conducting-power of certain 

 metals which have not yet been experimented upon in a state of purity. 



In the fourth part we point out, first, that the percentage de- 

 crement in the conducting-power of alloys between 0° and 100° is 

 never greater than that of the pure metals composing them ; secondly, 

 that the conducting-power of alloys decreases with an increase of 

 temperature (some bismuth alloys form an exception to this law) ; 

 thirdly, that in some cases the percentage composition of an alloy 

 may be deduced from its conducting-power, with the aid of the per- 

 centage decrement in its conducting-power ; fourthly, the method 

 which we have used for determining the class to which the metals 

 belong in respect to the conducting-puwer of their alloys ; and 

 fifthly, that the results which we have obtained and dc scribed in this 

 memoir fully bear out the views put forward in a former one on the 

 chemical nature of alloys. . 



" On the Peroxides of the Radicals of the Organic Acids." Bv Sir 

 B. C. Brodie, Bart. 



In a former notice published in the Phil. Mag. S. 4. vol, xvh\ 

 p. 301, an announcement was made of the discovery of a new group 

 of organic combinations, the peroxides of the radicals of the organic 

 acids — bodies which in the systems of the combinations of these 

 radicals occupy the same relative position as is held by the peroxides 

 of hydrogen, barium, or manganese in the systems of the combina- 

 tions of those elements. An account was given of the mode of 

 preparation and properties of two members of this group, the perox- 

 ides of benzoyle and of acetyle, C u H 10 4 and C 4 H 6 4 . The 

 present paper contains an extension of this inquiry. In it is given 

 an account of several other peroxides of monatomic radicals, the 

 peroxides of nitro-benzoyle, of cumenyle, of butyle, and of valeryle, 

 and also an inquiry into the action of the peroxide of barium on the 

 bibasic anhydrides. 



The nitro-benzoic peroxide is formed by the action of fuming nitric 

 acid on the peroxide of benzoyle. It stands to peroxide of benzoyle 

 in the same relation as anhydrous nitro-benzoic acid stands to anhy- 

 drous benzoic acid, and may be regarded as derived from that peroxide 

 by the substitution in it of two atoms of peroxide of nitrogen fof 

 two of hydrogen. The formula of the substance is C u H 8 (N0 2 ) 2 4 . 







Calculated. 



Found. 



c 14 .... 



.... 168 



.... 50-60 



, . . . 5060 



H 8 .... 



.. .. 8 .. .. 



2-41 



2-58 



N 2 .... 



.... 28 ... . 



8-43 



8-49 



o 8 .... 



.. .. 128 



.... 38-56 



. . . 38-33 





332 



100-00 



10000 



