TOLUENE. 281 



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

 obtained. 



Mauveine, C 2r H 24 Isr 4 . The sulphate (anilin-purple, 

 anileine, indisine, violine), (C 27 H 24 ^ 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. 



Sulphotoluenic acid, C 6 H 4 j gj^ oH is formed 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. 



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