92 Proceedings of the Royal Irish Academy. 



separated out. This process was repeated a number of times in order to 

 obtain the compound pure for analysis. 



•1940 substance gave 9 - -i c.es. moist nitrogen at 16" C. and 762 mm. P., 



corresponding to N = 5 - 66, 

 CH.sC.SjNa.X, requires X = 5S0. 



The pure compound is a dark-bluish amorphous powder which gives a 

 deep-red solution in water, and dyes unmordanted cotton a light-purple 



shad.-. 



9. Coupling of B< ■& -Disulphc A I with Pyrocatechin. 



OH SOaNa SON, OH 



I _ J I 



HO-/V-N-H-/ y / V-N=N , /X |-OH 



\/ S_ \ so/" \/ 



Tln> benzidine-sulphone-disulphonic a<id (22*3 grams) was tetrazotised in 

 the usual manner aftei which it was added to a cold Bolution of 30 grama 

 of Bodium carbonate with conatanl stirring. 12 grams of Pyrocatechin, 

 dissolved in a little water, were added immediately, and tin- stirring continued 

 foraday. Aftei -t aiding overnight the Bolution was heatou on a water-bath 

 to 80° C, and the colouring matter precipitated by the addition of common 

 salt, when it was filtered at tin- pump, dried, and ground. It was purified 

 as before by repeated separation, on cooling, from hot dilute alcohol. 



•1" a 10*8 c.cs. moist nitrogen ;it 16' ('. ami 763 mm. I'. 



corresponding to N = 7*90, 

 .11 .".X.N:,- requires N - 8-10. 



Tin- pure substance is a dark-bluish amorphous powder soluble in watei 

 to a dark-brown solution, and dyed cotton directly a light-brown. 



10. ■ -/> , A id with Resorcin. 



oil SOjXa OH 



I _ I 



/\- v _ s_ ' / ' _m _ w-/\ 



HO I -/ S-S I ! on 



The method adopted was similar t" thai used for Pyrocatechin. 

 22*3 mains of benzidine-sulphone-rlisuljihonic acid were dissolved in 150 c.cs. 

 of water, and tetrazotised with a concent ii t'-'l solution oi 7*2 grams oi sodium 



