THE PEEPAEATION OF ANIMAL TISSUES. 63 



gelatine is completely saturated and swollen, and 

 melt it in a water bath. Strain, whilst hot, through 

 flannel and make up the solution to 2 ounces. 

 Place the carmine in a mortar, add to it the 

 ammonia and 2 ounces of water, and leave it for 

 twelve hours. Filter, and add the acetic acid, drop 

 by drop, stirring all the while, until the ammonia 

 is completely neutralised. As the odour of the 

 ammonia becomes faint, the acid must be added 

 very cautiously. As long as there is free ammonia, 

 the fluid is dull red, but it becomes of a brilliant 

 colour as soon as the ammonia is neutralised. Now 

 mix the two solutions at a temperature of 40 C. 



DR. G-. SIMS WOODHEAD'S MASS. 



Take of Carmine, 4 parts by weight. 



Liq. Ammonia, 8 parts by measure. 



Gelatine (Cox or Coignet's), 10 parts by weight. 



Distilled Water, 100 parts by measure. 



Put the carmine in a mortar, and pour on the 

 ammonia, when an almost black paste will be 

 formed if the carmine is pure ; pour in the water, 

 and set the solution aside to be filtered. Place the 

 gelatine in a narrow glass jar, and add sufficient 

 distilled water to cover it, and allow it to stand 

 until the gelatine is thoroughly softened. Warm 

 the carmine solution in a pan of water, kept at 

 nearly boiling point over a Bunsen gas burner, and 

 add the gelatine; stir thoroughly, add a 10 per cent. 

 solution of acetic acid, drop by drop, until the 

 alkalinity of the ammonia is neutralised, and the 

 fluid shall be even slightly acid. The point at 

 which this takes place will be recognised by the 

 pungent odour of the ammonia becoming fainter and 



