192 PREPARATION AND MOUNTING 



Take 180 grains best carmine. 



^ fluid ounce of ammonia, commercial strong? li. 



viz., 0'92, or 15 ammonia meter. 

 3 or 4 ounces distilled water. 



Put these into a small flask, and allow them to digest with- 

 out heat from twenty-four to thirty-six hours, or until the 

 carmine is dissolved. Then take a Winchester quart bottle, 

 and with a diamond mark the spot to which sixteen ounces 

 of water extend. The coloured solution must be filtered 

 into the bottle, and to this pure water should be added 

 until the whole is equal to sixteen ounces. 



Dissolve 600 grains potash alum in ten fluid ounces of 

 water, and add to this, under constant boiling, a solution of 

 carbonate of soda until a slight permanent precipitate is 

 produced. Filter and add water up to sixteen ounces. Boil 

 and add the solution to the cold ammoniacal solution of 

 carmine in the Winchester quart, and shake vigorously for 

 a fe*v minutes. A drop of this placed upon white filtering- 

 paper should show no coloured ring. If much colour is in 

 solution the whole must be rejected, because, although 

 it is possible to precipitate all the colouring matter by 

 the addition of ammonia or alum, it is not well to do 

 so, as the physical condition of the precipitate is thereby 

 altered. 



Supposing the precipitation to be complete, or very 

 nearly so, shake vigorously for at least half an hour, and 

 allow it to stand until quite cold. The shaking must then 

 be renewed for some time, and the bottle filled up with pure 

 water. 



After allowing the precipitate to settle a day, draw off 

 the clear supernatant fluid with a syphon. Eepeat the 

 washing until the clear liquid gives little or no precipitate 

 with cnloride of barium. So much water must be left 

 with the colour at last that it shall measure forty fluid 

 ounces. 



