OF ARTS AND SCIENCES. 268 



several samples were convinced that the precipitate had a varying 

 composition, and therefore describe our work only because of a curious 

 observation made in the course of it. The salt was made by adding a 

 solution of cupric sulphate to an alcoholic solution of the sodium salt, 

 which need not be free from sodic hydrate ; the copper salt was ex- 

 tracted with ether, and obtained on evaporating the ethereal solution 

 as an orange mass, which when heated exploded with a blue flame. 

 It was insoluble in water, nearly insoluble in cold alcohol, soluble in 

 hot, and the yellow solution deposited the salt in rhombic ci-ystals ; very 

 soluble in benzol or chloroform ; insoluble in ligroine. 



We next substituted an alcoholic solution of cupric chloride for the 

 cupric sulphate, in hopes of getting a better result, when to our sur- 

 prise a product was obtained crystallizing from alcohol in long white 

 prisms, and melting in the crude state at 75°. This product was ob- 

 tained more than once, but as frequent crystallization was necessary 

 to purify it, we did not at first liave enough to bring it into a state fit 

 for analysis; and, on returning to the subject after some months, we 

 obtained under the same conditions nothing but the orange explosive 

 copper salt. Unfortunately, we had postponed work on this subject 

 till so near the end of the term that we were unable to give it the 

 careful study it seems to deserve, but its investigation will be continued 

 in this laboratory next year. 



Study of the Reactions by which Bromtrinitrophenylmalonic Ester 



is formed. 



The reactions by which the bromtrinitrophenylmalonic ester is 

 formed from the tribromtrinitrobenzol must consist in the replace- 

 ment of one of the atoms of bromine by the nialonic ester radical 

 CH(COOC2H5)2, and of another by hydrogen. The first of these pro- 

 cesses needs no explanation, but the mechanism of the second, the 

 replacement of the bromine by hydrogen, could be made out only by 

 experiment. Obviously, tlie first point to be settled was the form in 

 which the bromine was eliminated ; that is, whether as sodic bromide 

 alone, or partly as sodic bromide and partly as an organic com- 

 pound. For this purpose the following quantitative determinations 

 were made : — 



I. 10 grs, of tribromtrinitrobenzol, treated with the sodium malonic 

 ester from 15 grs. of malonic ester, gave after standing two 

 days and a half 8.83 grs. of argentic bromide, corresponding to 

 3.76 grs. of bromine. 



