HISTOLOGICAL METHODS. 179 



METHODS OF INJECTION. 



I. INJECTION MASSES FLUID AT THE ORDINARY 

 TEMPERATURE. 



333. Aqueous Solution of soluble Prussian Blue. 



Soluble Prussian blue can now be procured in the 

 market. The following, however, is the method in which 

 it may be prepared (Briicke). 



A. Dissolve 217 grammes potassium ferrocyanide in i 

 litre distilled water. 



B. Dissolve 100 grammes ferric chloride in i litre 

 distilled water. 



C. Make a cold saturated solution of sodium sulphate. 

 Mix i volume of A with two volumes of C, and mix i 



volume of B with 2 volumes of C. Pour B C very gradu- 

 ally into A C, stirring all the while, and let stand for a 

 day. Pour off supernatant fluid, and filter off the remain- 

 ing fluid from the precipitate. Wash the precipitate upon 

 the filter, with repeated small quantities of distilled water, 

 until it flows through distinctly blue. Press and dry the 

 deposit. 



For the purpose of injection, a 2 per cent solution of 

 the blue in distilled water is employed. The fluid may be 

 used cold, or it may be heated to the temperature of the 

 body. After injection, prevent the blue from diffusing 

 through the capillary walls by immersion in spirit (90 per 

 cent). If the colour fade, immersion in turpentine, especi- 

 ally in that which has been exposed to the air for some 

 time, or in acid, restores it. Mount in dammar ; glycerine 

 must be avoided. 



334. Beale's Prussian Blue injection. 



A. Mix i oz. glycerine with 4 oz. water. 



B. Add 60 minims tincture of ferric chloride (British 

 pharmacopoeia) to i oz. of solution A. 



C. Dissolve 1 2 grains potassium ferrocyanide in i oz. 

 of solution A. 



Pour B into C very gradually, with constant stirring and 



