192 PREPARATION AND MOUNTING 
Take 180 grains best carmine. 
3 fluid ounce of ammonia, commercial strength, 
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 few 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. Repeat the 
washing until the clear liquid gives little or no precipitate 
with chloride of barium. So much water must be left 
with the colour at last that it shall measure forty fluid 
ounces. 
