STAINING, PRACTICAL AND THEORETICAL 



DIPHENYLMETHANE GROUP 



Chromophore: \ 



C=NH 



This is a very small group. Only one dye, auramine O, is used 

 as a microscopical stain. This is used as a fluorchrome for tubercle 

 bacilli. It is a basic dye. 



AURAMINE O 



Michrome No. 42. Molecular weight 304. A basic dye, pH 7-0*. 

 Solubility at 15° C: water i-o%, absolute alcohol 4-0%. 



Note: Solutions of auramine should be prepared by shaking 

 the required quantity of the dye with the solvent at room tem- 

 perature: if the solutions are heated above 38-40° C decomposi- 

 tion takes place. 



(H3C)2N-/~\— C ^(^~\- N(CH3)2 



NH . HCl 



* 1% in neutral distilled water; see pages 17 and 29. 



54 



