224 INJECTIONS. 



solution, then rinsed and put for a few hours into water acidu- 

 lated with acetic acid. It is then washed on a sieve for several 

 hours in running water, dried on parchment paper, and 

 preserved as above. 



This injection mass is very well spoken of. 



Blue Gelatin Masses. 



447. Robin's Prussian Blue Gelatin Mass (see above, No. 436). 



448. Ranvier's Prussian Blue Gelatin Mass. (Traite, p. 119). 

 Twenty-five parts of a concentrated aqueous solution of 

 soluble Prussian blue (prepared as directed below), mixed with 

 1 part of solid gelatin. 



The mixture of the Prussian blue with the vehicle is effected 

 in the following manner : 



Weigh the gelatin, soak it in water for half an hour or an 

 hour, wash it, and melt it in a test-tube, in the water it has 

 absorbed, by heating over a water-bath. Put the solution 

 of Prussian blue into another test-tube, and heat it on the 

 same water-bath as the gelatin, so as to have the two at the 

 same temperature. Pour the gelatin gradually into the Prus- 

 sian blue solution, stirring continually with a glass rod. 

 Continue stirring until the disappearance of the curdy pre- 

 cipitate that forms at first. (Some gelatins produce a persistent 

 precipitate ; these must be rejected ; but it must be borne in 

 mind that the precipitate that invariably forms in even the 

 best gelatins disappears if the heating be continued. It is 

 essential to remember this when preparing Prussian blue and 

 gelatin mass.) As soon as the glass rod has ceased to show 

 blue granulations on its surface on being withdrawn from the 

 liquid, it may be concluded that the Prussian blue is com- 

 pletely dissolved. Filter through new flannel, and keep the 

 filtrate at 40 over a water-bath until injected. 



The soluble Prussian blue for the above mass is prepared 

 as follows : 



449. Soluble Prussian Blue for Injection Masses (RANVIER, 

 Ibid). Make a concentrated solution of sulphate of peroxide of 

 iron in distilled water, and pour it gradually into a concentrated 

 solution of yellow prussiate of potash. There is produced 

 a precipitate of insoluble Prussian blue. (An excess of 

 prussiate of potash ought to remain in the liquid; in order to 



