STAINING, PRACTICAL AND THEORETICAL 



NAPHTHOL YELLOW S 



Michrome No. 191. Molecular weight 358. An acid dye, 

 pH 8-15*. Solubility at 1$° C : water i2-$%, absolute alcohol o • 65 % 



ONa 



NaOaS- 



NO2 



NO2 



PICRIC ACID 



Michrome No. 707. Molecular weight 229, pH i -35*. Solubility 

 at 15° C: water 1-2%, absolute alcohol 9%. 



OH 



O 



O2N 



NO2 O2N— I 



or ' 



-NO2 



NO2 NO . OH 



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



58 



