OF ARTS AND SCIENCES. 55 



these papers appeared in 1866, when the nature of aromatic isomeres 

 was very imperfectly understood. 



For the reason given above, we determined to prepare the para- 

 chlorbenzylchloride from perfectly pure parachlortoluol, and hoped 

 that it might be a solid, instead of the oily liquid described by our 

 predecessors ; indeed, it seemed hard to believe that it could be a 

 liquid, as the parachlortoluol melts at 6£° (Hiibner and Majert), and 

 we had already found that the introduction of bromine into the side- 

 chain raised the melting-point to 48 1°. 



Preparation. Parachlortoluol was made from pure paratoluidine 

 by treatment with hydrochloric acid and potassic nitrite, according to 

 a modification of the method of Hiibner and Majert, * described in 

 connection with parachlorbenzylbromide in the first paper f of this 

 series. The 31 grs. that we obtained distilled over completely be- 

 tween 160° and 161°, and froze between 4° and 5° in white plates 

 looking exactly like parabromtoluol, which melted from 7° to 7|-°. 

 These results agree essentially with those of Hiibner and Majert,* 

 who found the boiling-point 160|°, the freezing-point a little above 

 0°, and the melting-point 6|-°. To convert this into parachlorbenzyl- 

 chloride, a stream of chlorine was passed into it while it stood in a 

 paraffine-bath heated to 166°: when the increase in weight showed 

 that somewhat more than the calculated amount of chlorine had been 

 taken up (the 27 grs. of parachlortoluol used had become 35 grs. 

 instead of 34.3 grs.), the chlorine was stopped, and the product put 

 in a freezing mixture of ice and salt, where it partially solidified in 

 white needles, which were drained on the filter-pump, and recrystal- 

 lized from alcohol. The yield was very small, and all attempts to 

 get more from the mother-liquors were fruitless. The following 

 analyses of the substance dried in vacuo show that it is the expected 

 parachlorbenzylchloride. 



0.6760 gr. of substance gave 1.2930 gr. of C0 2 and 0.2458 gr. of 

 H 2 04 



0.2755 of substance gave, by Klobukowski's § modification of Emil 

 Kopp's method, 0.4946 gr. AgCl. 



* Hiibner and Majert, Ber. D. Ch. G. vi. p. 794. 



t These Proceedings, XII. (n. s. IV.) p. 218. 



\ Combustion of these parachlorbenzyl compounds with plumbic chromate 

 alone was found to yield good results much more easily than the more usual 

 method of combustion in a stream of oxygen, and therefore was used in the 

 analysis of all these substances. 



§ Klobukowski, Ber. Dt. C. G. 10, p. 290. 



