THE COAL-TAR COLORS 141 



Mauvein (hydrochloride), or Aniline Violet, CarHgsNiCl, made by the 

 action of chromic acid on aniline containing some toluidine. 



Methyl Orange, CwHiaNsSOsNa, made by the successive action of nitrous 

 acid and methylaniline upon para-amidobenzene-sulphonic acid; it is the 

 sodium salt of helianthin. 



Methyl Violet, C 2 4H 2 8N 3 C1, made by oxidizing dimethyl-aniline with 

 metallic salts. 



Methylene Blue, CieHisNsSCl, made by heating amido-dimethylaniline 

 with sulphide of iron. 



Naphthol Yellow, CioH 5 N 2 08SK, made by the action of nitric acid on 

 a-naphthol-trisulphonic acid. 



Nigrosin, CigH^Ns, made by heating aniline salts with nitrobenzene. 



Night Blue, C 3 8H 34 N 3 O (the hydrochloride of this is the commercial dye), 

 made by heating pararosaniline with aniline and benzoic acid. 



Pararosaniline (chloride), CigHigNsCl, made by oxidizing a mixture of 

 para-toluidine and aniline with arsenic acid, or nitrobenzene. 



Phenylene Brown. See Aniline Brown above. 



Ponceaux, or Bordeaux. Various derivatives of azonaphthalene. 

 "Ponceau 3R," Ci9Hi6N 2 O7S 2 Na2, is made by combining diazocymene 

 hydrochloride with /2-naphthol-disulphonic acid. 



Primulin, CnHi^^ (?), made by the action of sulphuric acid on 

 thiotoluidine. 



Resorcin Yellow, or Tropseolin O, C^HieNjjOsS, made by the action of 

 diazobenzene-sulphonic acid on resorcin. 



Rhodamine (hydrochloride), C 2 8H 3 iN 2 3 Cl, made by the action of 

 phosphorous trichloride on fluorescein, and treatment of the product with 

 diethylamine. 



Roccellin, C 20 Hi 3 N 2 O 4 SNa, made by the action of /?-naphthol on the 

 diazo-compound of naphthionic acid. 



Rosaniline. See Fuchsin above. 



Rose Bengale, C 2 oH 4 Cl2l 2 O 5 K 2 , made by the successive action of chlor- 

 ine and iodine upon fluorescei'n. 



Rosolic Acid, C 20 Hi 6 O 3 , closely allied to aurin; neither aurin nor rosolic 

 acid is specially valuable. 



Safranin, C 2 iH 2 iN 4 Cl, made by the oxidation of a mixture of tolulene- 

 diamine and aniline or toluidine. 



Tropoeolin. This name is applied to various compounds made by the 

 successive action of nitrous acid and phenols upon amidobenzene sul- 

 phonic acids. See Resorcin Yellow above. 



Uranin, C 2 oGi O5Na 2 , the sodium salt of fluorescein (which also see 

 above). 



Victoria Green. See Malachite Green above. 



Victoria Orange. See Aniline Orange above. 



BIBLIOGRAPHY. Schultz, Die Chemie des Steinkohlenteers (Brunswick, 

 1890); Villon, Traite pratique des matieres color antes artificielles (Paris, 

 1890) ; Cazeneuve, Repertoire analytique des matieres colorantes artificielles 



