INJECTION GELATIN MASSES. 303 



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

 acidulated 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 mass is very well spoken of. 



487. Other Carmine Gelatin Masses. THiEKscH's,see.4re7i./. mik. 

 Anat., 1865, p. 148. GERLACH'S, see EANVIEK, Traite, p. 118. CAKTEB'S, 

 see BEALE, p. 113. DAVIES, see his Prep, and Mounting of Mic. Objects, 

 p. 138. 



Blue Gelatin Masses. 



488. ROBIN'S Prussian Blue Gelatin Mass (see above, 482). 



489. KANVIER'S Prussian Blue Gelatin Mass (Traitr, p. 119). 

 Twenty-five parts of a concentrated aqueous solution of 

 soluble Prussian blue (prepared as directed below) mixed 

 with one part of solid gelatin. 



The mixture of the Prussian blue with the vehicle is 

 effected in the following mauner : 



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 

 Prussian 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 per- 

 sistent 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.) 

 As soon as the glass rod has ceased to show blue granula- 

 tions on its surface on being withdrawn from the liquid, it 

 may be concluded that the Prussian blue is completely dis- 

 solved. 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 : 



490. Soluble Prussian Blue for Injection Masses (EANVIEE, 

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



