60 



Journal of Applied Microscopy. 



convenience we may divide the rosanilins 

 into: 



Acid 



1 



(Fuchsin) 



Basic 



(Fuchsin) 



1 Hydrochloride. 

 Salts ^ Nitrate. 

 I Sulphate. 



^- { ^fruchsiii) } Picrate of Rosanilin. 



Example, contrast produced in blood 

 elements: 



Acid Fuchsin stains deeply the most dif- 

 ferentiated parts of cells. Red cells 

 deeply, leucocytes faintly, nuclei not 

 at all stained. 



Basic Fuchsin stains the least differen- 

 tiated parts, nuclei most deeply, body 

 leucocytes to a less extent, red corpu- 

 scles least of all. 



Anilin dyes should be called "amine" 

 dyes, as it includes dyestuffs from 

 naphthylamine as well as from anilin 

 and toluidine. They are classed as: 



I. Anilin. 



(a) Rosanilin group, and the most 



important. 



(b) Indulins and Safranins. 



(c) Oxazms. 



(d) Anilin black. 



(e) Coloring matters with sulphur 



(Thionins.) 

 n. Phenol Dyes. 



III. Azo Dyes. 



IV. Artificial Indigo, 

 v. Anthracen Dyes. 



Rosanilin salts are derivatives of two 

 hydrocarbons; triphenylmethane, C19 H^e 

 and tolydiphenylmethane, Cjo Hjg. 



( C„H6 ) 



^CjoHia 



( CeH^CHj 



r J CeHg 



^ JCeH^ 



(h 



-GjgHie. 



The carbon atom which joins the three 

 benzene rings to each other is distin- 

 guished as the "methane carbon." To 

 arrive at the value and use of this group 

 of salts we must first briefly look over 

 some of the technical points. If we 

 replace one H atom by NH^ in two or 

 three phenyl groups, and further the H 

 of the NHo group is replaced by methyl, 

 benzyl, phenyl, etc., we obtain a series 

 of nitrogenous compounds the value of 

 which comes later, e. g. : 



1. Diamldotriphenylmethane. 



2. Triamidotriphenylmethane. (para leu- 



cine.) 



3. Tetra - methyldiamido triphenylme- 



thane. (Leucobase of malachite 

 green.) 



4. Triphenylleucaniline. 



5. Pentamethylleucaniline. 



These compounds, "leucobases," are 

 colorless and yield colorless salts with 

 acids. By oxidation they are transposed 

 more or less readily into the color 



bases, which differ from the leucobases 

 by containing one atom of oxygen. 



(CeH.NH,) 

 C < CeHiNHj V= Para Leucanilin. 

 iCeH.NHj 



CeH^NH, 

 CeH^NHj 

 CeH^NH., 

 OH 



Para Rosanilin. 



The color bases are nearly always col- 

 orless. They unite with acids, giving 

 off water to form colorless salts, the real 

 dyestuffs. The exact method is not 

 well known except in the case of para- 

 rosaniline. Besides these mono-acid, 

 colored salts, the bases yield a series of 

 compounds containing two or more 

 equivalents of acid, generally yellow or 

 brown. Thus, rosanilin hydrochloride, 

 magenta, C,o H19 N3 H CI, will unite 

 with two more molecules of HCl to form 

 the triacid salt C20 Hu N,. 3HCI. This 

 explains the behavior of the coloring 

 matters of this group in aqueous solu- 

 tions, or on fiber, towards concentrated 

 acids, viz., H, SO4, H NO3, etc. Decolor- 

 ization takes place, but on adding water, 

 the acid salt is decomposed and the 

 original color is restored, as note the 

 tubercular sputum methods. This will 

 perhaps aid the student to remember to 

 dip his cover in the acid and then to 

 wash in water, which seem so easily for- 

 gotten in this work and so much more 

 sure a test than to return to alco- 

 hol, which is sometimes advised 

 by some teachers. Commercial ani- 

 lin red is magneta, but not a uni- 

 form substance, and is a mixture 

 of the salts of two bases. Para- 

 rosaniline, C19 Hjo N3 O (a derivative of 

 triphenylmethane) and Rosanilin, C^o 

 H,i N3 O (a derivative of tolyphenyl- 

 methane). 



If triphenylmethane is treated with 

 H NOa, the trinitrotriphenylemethane is 

 gotten, this then treated with chromic 

 acid gives trinitrophenylcarbinol, which 

 when partially reduced by zinc and acetic 

 acid is changed to pararosaniline, i. e., 

 triamidotriphenylcarbinol. The para- 

 rosanilin at once unites with the acetic 

 acid and we get acetate of pararosan- 

 iline. As rosaniline is also prepared from 

 another derivative, tolydiphenylmethane, 

 we get a similar compound, but its action 

 is different on tissues. Magenta is man- 

 ufactured in various ways, but by the 

 almost obsolete mercury method we 

 obtain a very pure nitrate of rosanilin, 

 which by double decomposition and 

 common salt is converted also into 

 rosanilin hydrochloride (Cjo H19 N3 HCl). 

 The nitrate (C^o H,9 N3, H NO3) is known 

 in commerce as azale'ine when prepared 

 by this method, hence the name given 

 under the title of Fuchsin or Rosanilin 

 as a synonym. 



