9O PRACTICAL HISTOLOGY. 



place it in a beaker in a water-bath. When the gelatine is dissolved 

 by the water which it has absorbed, add to it stirring vigorously 

 the solution of carmine, which yields an amrnoniacal solution of 

 carmine in gelatine. 



When the carmine mixture is on the water-bath make a solution 

 of 



Distilled water ..... 2 parts. 

 Glacial acetic acid i part. 



Pour the acid drop by drop into the mass, stirring thoroughly 

 all the time with a glass rod. The acid is to neutralise the excess 

 of ammonia. This requires great attention. It is by the odour 

 that one recognises when the fluid is neutralised. As the acid is 

 added the ammoniacal odour diminishes, and there is at last a 

 faint acid odour. This is the moment to stop adding the acid. 

 Towards the end of the operation it is best to dilute the acid 

 somewhat. 



Filter the mass through new flannel. 



3. Carmine Gelatine Mass (Carter'*) (Fearnley's method). 



Carmine 



Strong ammonia 

 Glacial acetic acid 

 Coignet's French gelatine 

 Water 



3 grams. 

 6 cc. 



6 



7 grins. 

 80 cc. 



Cut up the gelatine into small pieces and place it in 50 cc. of 

 the water to swell up, i.e., for four or five hours. Rub up the 

 carmine in a mortar with a little water and add the ammonia. 

 Let it stand for two hours and then pour it into a bottle, rinsing 

 the mortar with the remainder of the water. Place the swollen- 

 up gelatine, and any remaining water unabsorbed by it, on a 

 water-bath until it melts. To the dark purple carmine fluid add 

 the acid (a few drops at a time), mixing the two thoroughly, and 

 as soon as the fluid changes to a crimson stop adding the acid. To 

 the melted gelatine add the crimson carmine little by little and 

 keep stirring all the time. 



This mass may be kept in a cool place for a long time if its 

 surface be covered with methylated spirit. Before using it, 

 dissolve it on a water-bath, and filter it through fine flannel 

 wrung out of hot water. The best gelatine to use is French 

 gelatine Coignet's. 



4. Blue Mass. The mass is made with gelatine coloured with 

 soluble Prussian blue or Briicke's blue. It is very difficult to 

 obtain a pure sample of Briicke's blue, but this can now be had 

 from Dr. Griibler of Leipzig. Use a saturated watery solution of 

 Briicke's blue. 



Weigh 5 grms. of gelatine, and treat it exactly as described 



