NEW METHYLENE BLUE N 



Synonym: Methylene blue NN. 



c. I. NO. 927 



CHi'CHa 



\ 



H 



CH3 CH3 CH.CH3 



. I I / 



N /\_S_/\=N_H 



CI 



(A basic dye; absorption maxima about [6S6.4], 588.) 



This dye has practically never been called for in microscopical 

 work. The most interesting fact concerning it which has come to 

 light relates to the VanWijhe technic as applied by Louise Smith 

 (1920) for staining the cartilage of frogs. The latter specified 

 methylene blue, but the results could not be duplicated with any 

 domestic or foreign methylene blue subsequently obtained. When 

 furnished thru the Commission with samples of various stains to 

 try, it was found that her earlier results could be duplicated with 

 new methylene blue — a fact which not only implies mislabeling of 

 her original supply of methylene blue, but suggests that new methy- 

 lene blue may have some value in histological work. 



3. THE OXAZINS 



This group is like the thiazins in chemical formula except that 

 the sulfur atom is replaced by an oxygen atom. Only a few of the 

 dyes find use in microscopic technic, and they are not stains having 

 very general application. 



BRILLIANT CRESYL BLUE C. I. NO. 877 



Synonyms : Cresyl blue 2RN or BBS; brilliant blue C. 



CHj'CHa 



N 



CH.CH 



O 



.NH, 



3 ^AA2 



CH. 



CI 



(.4 basic dye; absorption maxima about 631.8 [579.5]) 



This dye is prized for certain special work on account of its 

 highly metachromatic properties. Its chief biological use is for 

 staining blood to bring out the platelets and the reticulated blood 

 corpuscles. 



Brilliant cresyl blue proved one of the most difficult stains to 

 obtain in good quality since the war. The problem was finally 

 solved however, and the pre-war stain has not only been equalled 

 but surpassed. 



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