APPENDIX. S73 



Carmine. (Frey's method.) 



a. Carmine 0'3 grm. 



Glycerine 30-0 „ 



Alcohol 4-0 „ 



Distilled water 30-0 „ 

 Ammonia q. s. 



Add the distilled water to the carmine, and then add 

 dilute ammonia drop by drop until the carmine is 

 dissolved, taking care that the least possible excess 

 is added. If the solution smells strongly of ammonia 

 expose it in a flat vessel to the sunlight for a day 

 or two. Finally add the glycerine and alcohol, and 

 shake. It should be kept in a stoppered bottle, 

 since otherwise the ammonia evaporates and the 

 carmine is precipitated. 



It may be diluted with water to any extent required. 

 In the strong solution tissues hardened in chromic 

 acid or chromium salts may be left for days or weeks 

 without being over-stained. 



Asa rule sections stain better with cai-mine when they 

 are left in a dilute solution for 12 to 24 hours. 



In another glass, under the same bell-jar as the sections, 

 a little dilute solution of ammonium carbonate may 

 be placed. 



If sections are too deeply stained with carmine, or if 

 there is a precipitate of carmine upon them, they 

 should be placed in very dilute ammonia and gently 

 moved about in it; as soon as the excess of car- 

 mine is removed, they should be poured into a large 

 quantity of water and all trace of ammonia washed 

 awav. 



