ON THE CHEMISTRY AND STAINING PROPERTIES OF CERTAIN DERIVATIVES OF THE METHYLENE BLUE GROUP WHEN COMBINED WITH EOSIN.

1. Eosinate of thionin gives very satisfactory staining for blood smears. It is easily prepared and dissolves readily in methylated spirits. 2. In the methods heretofore employed for making mixtures of eosin and methylene blue derivatives, the eosinates of methylene violet and methylene azure are present in very small quantities or are altogether absent. 3. Thionol and thionin are probably formed in methylene blue which has been long boiled with dilute alkalies and silver oxide. 4. Good stains of eosin and methylene blue derivatives can be obtained by a variety of manipulations. 5. Methylated spirits is more economical as a solvent for this stain and better adapted for the simple technique above described than is methyl alcohol. There is some evidence that the staining act is of a chemical nature.