60 W. H. E M I G 



923. Methylene Azure, Azure I is a basic dye, light 3; 1/10 

 gram in 95 ml. of distilled water, 5 ml. of 5 per cent ammonium 

 alum, and £ ml. of acetic acid. Methylene Blue in solution changes 

 to Methylene Azure by oxidation. Methylene Azure includes a 

 mixture of Azure A and Azure B. Azure C is another oxidation 

 product of Methylene Blue. Azure II is a mixture of equal parts 

 of Methylene Blue and Methylene Azure. All of these dyes are 

 polychromatic, a property which makes them valued for blood 

 stains. The preparation of blood stains includes the oxidation of 

 Methylene Blue and the addition of eosin. 



By staining a section of pine wood in Methylene Azure or 

 Methylene Blue for 15 minutes, the torus becomes bright red while 

 the walls of the tracheids are blue; by staining for a longer time 

 only a blue is obtained. Unfortunately, these colors are not fast. 

 The addition of acids, alkalies, or ammonium alum greatly affects 

 the stain. Acid solutions of the dye react slowly with a better dif- 

 ferentiation than neutral solutions; an alkaline solution will stain 

 25 times more rapidly than an acid solution. The addition of am- 

 monium alum intensifies the color in either dye-solution. 



924. Methylene Green is a basic dye, light 3 ; £ gram in 95 ml. 

 of distilled water, 5 ml. of 5 per cent ammonium alum, and -J ml. 

 of acetic acid. In acid solutions of the dye, plant tissues are stained 

 green to blue-green. The intensity of the color is reduced but more 

 clear in differentiation if ammonium alum is present in the stain. 

 This dye is the best of the green basic dyes; it provides a good 

 counterstain after Acid Fuchsine, C. I. No. 692, Biebrich Scarlet, 

 C. I. No. 280, or Crocein Scarlet MOO, C. I. No. 252. 



925. Toluidine Blue O is a basic dye, light 3. Plant tissues 

 become blue similar in most respects to Methylene Blue. It may be 

 used as a substitute for Thionine, C. I. No. 920, or Azure A, C. I. 

 No. 923. 



926. Rhoduline Blue GO, Thionine Blue GO is a basic dye, 

 light 4. Plant tissues are stained blue or blue-green that is similar 

 to but not so fast as Methylene Blue, C. I. No. 922. 



927. New Methylene Blue, N, NSS is a basic dye, light 2 to 3 ; 

 J gram in 95 ml. of distilled water, 5 ml. of 5 per cent ammonium 



