APPENDIX 3 



EXPERIMENTS ON DYEING 



CONTENTS 



Preparation of pararosaniline page 321 



Electrophoresis of dyes 321 



Diffusion of dyes 322 

 The effect of alkaUnity and acidity on dyeing with 



basic and acid dyes 323 

 The effect of acid alcohol on tissues coloured with 



basic and acid dyes 324 



The effects of fixatives on the subsequent action of dyes 325 



Preparation of pararosaniline 



Put about 1-5 ml of colourless (freshly distilled) aniline and a large 

 crystal of paratoluidine in a test-tube. Scatter some powdered 

 mercuric chloride down the side of the test-tube. 



Heat strongly over a Bunsen burner, shaking the aniline on to 

 the mercuric chloride. A magenta colour will suddenly develop. 

 Stop heating while there is still some fluid in the tube. 



Electrophoresis of dyes 

 The apparatus is briefly described on p. 189 and illustrated in 



fig- 23. 



Prepare buffer solution from 'reagent-grade' chemicals as 



follows : — • 



— Na9HP04. Make up 9-466 g of the anhydrous salt to 500 ml 

 7-5 

 with distilled w^ater. 



^ KH,PO,. Make up 9-078 g of the salt to 500 ml with dis- 



tilled water. 



For an experiment at pH y-i, mix 66 ml of the Na2HP04 

 solution, 34 ml of the KH2PO4 solution, and 100 ml of distilled 

 water. This is 'buffer solution A'. 



Prepare agar gels as follows : — 



For the large U-tube. Put i-2 g of agar in 120 ml of distilled 

 X 321 



