224 PROCEEDINGS OF THE AMERICAN ACADEMY 



In 1869, Br. Rarlziszewski * obtained a substance which he called 

 parabromalphatoluylic acid, by the action of bromine in the cold upon 

 alphatoluylic acid ; he does not describe it fully, but only says that it 

 crystallizes in prisms melting at 76^, and gives baric and calcic salts 

 crystallizing in warts, and easily soluble in water and alcohol, by 

 oxidizing it with potassic dichromate and dilute sulphuric acid he 

 obtained nothing but parabrombenzoic acid melting at 251*^. He also 

 obtained in the same operation another acid containing bromine, which 

 melted at 99^, and was not further examined. The discrepancy 

 between my results and those of Radziszewski, is j^robably due to the 

 fact that he did not obtain a pure parabromalphatoluylic acid, but that 

 the two acids observed by him were mixtures of para and ortho com- 

 pounds, with perhaps some of the phenylbromacetic acid, CgH-CHBrC 

 OOH, melting-point 82", discovered by him in conjunction with 

 Glaser,t and which he shows in the paper under discussion, is formed 

 from the alphatoluylic acid by the action of bromine at 150'*. The 

 l^resence of a small quantity of orthobromalphatoluylic acid could 

 easily lower the melting-point from 114.^5 to 99°, or even 76" ; and, 

 as it would be entirely consumed by oxidizing with jiotassic dichromate 

 and sulphuric acid, such a mixture would yield only parabrombenzoic 

 acid. On the other hand, my acid being prepared from pure parabrom- 

 beuzyl-bromide, by jDrocesses in which the temperature never rose 

 above 100°, must be perfectly free from isomeres ; and this view is 

 confirmed by the fact that its melting-point is higher than that of the 

 acid obtained by Radziszewski. 



Amynonic parahromalphatoluate obtained by dissolving the acid in 

 ammonic hydrate, and driving off the excess of ammonia on the water- 

 bath, crystallized in long curving groups of colorless needles very 

 soluble in water. 



Argentic 'parahromalphatoluate ( C^JIJir. CH.^ CO OAg.) was preci- 

 pitated by adding the ammonic salt to argentic nitrate, as a white 

 curdy mass similar in appearance to chloride of silver ; it was washed 

 with cold water, and dried at GO". 



0.3106 gr. of the salt dissolved in dilute nitric acid, and precipitated 

 with hydrochloric acid, gave 0.1375 gr. AgCl. 



Required for C-Br-HgCO., Ag. Found. 



Silver 33.57 33.33 



* Radziszewski, Ber. D. Ch. G., 1869, p. 207. 

 t Zeitschr. Chem., 1868, p. 110. 



