374 APPENDIX. 



Most preparations stained with carmine are best pre- 

 served in glycerine containing 1 p. c. formic acid 

 1-16 Sp. Gr. 



Picrocarminate of Ammonia or Picrocarmine. 



Prepare a saturated solution of picric acid, and to it 

 add a saturated ammoniacal solution of carmine till 

 a precipitate occurs. Evaporate in a water-bath till 

 the volume is reduced by four-fifths. Filter, and 

 evaporate the filtrate to dryness. A crystalline 

 mass of picrocarmine is thus obtained. It dissolves 

 readily in distilled water ; a 1 to 5 p. c. solution 

 should be made, and further diluted as occasion 

 requires. 



If the picrocarmine is found to stain sections too 

 yellow, a little Prey's carmine may be added to it, 

 and the mixture filtered. 



Most of the yellow colour may however be removed 

 from tissues stained with picrocarmine by repeated 

 washing with water or alcohol. 



Picrooarmine after being used may be filtered and used 

 again. 



Borax carmine. 



Borax 4 parts 

 Carmine 2 '5 

 Water 100 



"Warm until the carmine is dissolved, being careful not 

 to let the mixture boil. When the fluid is cold, add 

 an equal volume of 70 p. c. alcohol and filter. 



