TOLUENE. 281 



Anilin-green (Iodine-green), C 20 H 16 (CH 3 ) 3 K(CH 3 ) 2 ! 2 

 + H 2 0, is prepared by heating 1 part of rosanilin ace- 

 tate, 2 parts of methyl iodide, and 2 parts of methyl 

 alcohol in closed vessels at 100. The mass is distilled 

 for the purpose of removing volatile products, and the 

 residue exhausted with water, with an addition of 

 common salt, by which means the green dye is dis- 

 solved, and a violet dye remains undissolved. Pure 

 iodine-green crystallizes in prisms with a green metal- 

 lic lustre, resembling that of cantharides. The anilin- 

 green of commerce consists chiefly of the picrate, pre- 

 pared by adding picric acid directly to the solution 



Mauveine, C 27 H 24 N 4 . The sulphate (anilin-purple, 

 anileine, indisine, violine), (C 27 H 24 N 4 ) 2 .H 2 S0 4 , is produced 

 by mixing a dilute solution of anilin sulphate (con- 

 taining toluidin) with a dilute solution of potassium 

 bichromate. The base, separated from this by means 

 of potassa, is a crystalline, almost black, glistening 

 powder, that dissolves in alcohol, forming a violet so- 

 lution, which turns purple on the addition of acids. 

 Very stable monatomic base. Decomposes ammonium 

 salts. The salts crystallize and have a green metallic 

 lustre. 



Anilin-brown is obtained by heating anilin-violet 

 or anilin-blue, with anilin hydrochlorate at 240. 

 Aldehyde-green is prepared by heating rosanilin sul- 

 phate, sulphuric acid, and aldehyde together, and treat- 

 ing the resulting blue dye with sodium hyposulphite. 



{OH 3 

 SO 2 OH is formecl in 



two isomeric modifications (para- and ortho-), when 

 toluene is dissolved in weak fuming sulphuric acid. 

 There is a very large number of varieties of the sub- 

 stitution-products of these acids known. 



24* 



of xm 



