STAINING, PRACTICAL AND THEORETICAL 



5. The dried precipitated dye is then ground to a homogeneous 

 powder with: 



I '75 gm. of disodium hydrogen phosphate 

 (Na2HP04, 2H2O) 



in a glass mortar, and stored in a well-closed glass tube until 

 required for preparing the staining solution. 



Notes: 



[a) The yield of the dye powder (without sodium hydrogen 

 phosphate) is between 0-35 gm. and 0-5 gm. 



{b) When only very small quantities of the stain are required it 

 is recommended that one-fifth of the total yield of the dye should 

 be mixed with 0-35 gm. of the sodium hydrogen phosphate and 

 dissolved in 100 ml. of distilled water, and the remainder of the 

 dry dye, which keeps well, should be stored until required for use. 



{c) J.S.B. stain No. i solution requires about two weeks to 

 mature before it is ready for use. 



Note: Add a few drops of chloroform as a preser- 

 vative, to inhibit the growth of air-borne micro- 

 organisms, otherwise the stain is liable to deteriorate 

 within a few days. 



B. Buffered wash water, pH 6 -2-6 -6 



(i) Disodium hydrogen phos- 

 phate (Na2HP04, 2H2O) 0-22 gm. 



Potassium dihydrogen phos- 

 phate (KH2PO4) . . • ■ 074 gm. 



or 



(ii) Simply dissolve i Michrome 

 buffer tablet, pH 6-5, in 

 100 ml. distilled water 



254 



