523 



in oily globules, which only gradually solidify. Ammonia likewise 

 separates the phenylene-diamine from its saline compounds; the 

 slightest excess, however, redissolves it, and the solution is apt to 

 become brown, and then contains products of transformation. This 

 observation explains in a measure why the diatomic base cannot be 

 conveniently obtained by the usual method of reduction by sulphide 



of ammonium. 



Toluylene-diamine. 



This substance is a crystalline solid. It dissolves freely in water, 

 forming an alkaline solution. It is likewise soluble in alcohol, and 

 less so in ether. Toluylene-diamine is one of the most beautiful 

 compounds I have ever seen. From boiling water it crystallizes 

 in needles, which frequently acquire an inch in length. Like 

 phenylene-diamine, this compound is apt to assume a yellowish tint 

 in contact with the air. Crystallization from water does not remove 

 this tint, which only yields to treatment with animal charcoal. The 

 aqueous solution of toluylene-diamine rapidly acquires a dark-brown 

 colour. The new substance fuses at 99, and distils without change ; 

 the boiling-point is above 280, a little higher than that of phenylene- 

 diamine. I shall, however, determine the boiling-points more accu- 

 rately as soon as I shall have procured myself larger quantities of 

 both substances. 



The analysis of toluylene-diamine has led to the expression 

 C,H 10 N,=(C 7 H 6 )" 



- 



This formula was verified by the examination of a sulphate crystal- 

 lizing in perfectly well-formed, long and rather thin prisms, apt to 

 assume a beautiful pink colour, which were found to contain 



The nitrate forms long needles, 



very soluble in water and alcohol. 



The bromide crystallizes in short prisms, likewise soluble in water 

 and alcohol, having the composition 



