Certain Neio Derivatives in the Aromatic Series. 



189 



dissolved in water rendered alkaline by the addition of enough sodic 

 hydrate to effect a solution, was added when the dye was immediately 

 formed. The reaction could be facilitated by stirring, and by warm- 

 ing the solution to about eighty degrees C. The dye was salted 

 out in the usual manner, filtered, pressed, dried, and analysed. All 

 the dyes have the same elementary composition, and analysis gives 

 the formula — 



CjoHg.SOsH.N = N.Cj^H^.OH.SOgH.SO.H. 



The dyes are reddish powders, readily soluble in water. Hydro- 

 chloric acid, even concentrated, produces no perceptible change in 

 the color on the fibre ; concentrated sulphuric acid on the dry 

 powder shows a change to a pink of an eosine shade ; the dyes are 

 insoluble, as a rule, in alcohol, and are exceedingly fast to the action 

 of sunlight. 



The naphtylamine sulphonic acids which can be used are — 

 Alpha-Naphtylamine-sulphonic acid, 1 : 2, patent No. 56,563, 



NH, 



\/ 



\ /\ 



SO3H 



Cleve's alpha-Naphtylamine-sulphonic acid, 1 : 3, 



NH., 



/ 



.SO3H 



Naphthionic acid, 1 : 4, 



NH., 



\ 



\ 



\.. 



SO.H 



