64 METHODS OF MICROSCOPICAL RESEARCH. 



fainter, and that of the acid substituted, whilst the 

 fluid loses its bright carmine, transparent colour, 

 and turns a dull brownish-red. 



BLUE INJECTION MASS. 



Take of Soluble Prussian Blue, 4 drachms. 

 Gelatine, 4 ounces. 

 Distilled Water, 20 ounces. 



Thoroughly mix the blue powder in a mortar 

 with half the water. Treat the gelatine as directed 

 in the case of the red mass, and add the blue solu- 

 tion very gradually, and with constant stirring, to 

 the liquefied gelatine. Filter through fine flannel. 

 The greatest care must be exercised that no trace 

 of alkali shall enter into the composition of this 

 mass all the vessels used in making it should be 

 carefully washed with acidulated water, and the 

 purest distilled water must be used in its prepara- 

 tion. Its colour is liable to fade and sections 

 injected with it, especially when mounted in 

 balsam, lose their colour after a time. It is better, 

 therefore, to mount all specimens injected with 

 Prussian blue in a slightly acid medium glycerine 

 jelly prepared with boracic acid pure glycerine 

 with a small proportion of acetic acid, or Farrant's 

 medium are the best preservatives for these injec- 

 tions. 



BLUE INJECTION MASS. 



(Robin's modification of Dr. Beetle's Prussian Blue) is made 

 as follows : 

 Take (a) Sulphocyanide of Potassium, saturated solution 



90 c.c. 



Glycerine, 50 c.c. 



(b) Liquid perchloride of Iron at 30, 3 c.c. 

 Glycerine, 50 c.c. 



