GELATINOUS AND ALBUMINOUS INJECTION-MASSES           269
411. Gelatin Injection-mass (Carmine) (Davies and Dale's
formula 1)
Take-
180 grains best carmine.
I fluid ounce'of ammonia, commercial strength, viz.
0-92 or 150 ammonia meter.
3 or 4 ounces water.
Digest without heat until the carmine is dissolved. Filter
and add water until the whole is equal to sixteen ounces.
Dissolve 600 grains potash alum in ten fluid ounces of
water, and add, under constant boiling, 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 carmine solution and shake vigorously for a few
minutes. A drop of the liquid placed upon white filtering
paper should show no coloured ring. If much colour is in
solution the whole must be rejected. If the precipitation is
complete or nearly so, shake vigorously for at least half an
hour, and allow the fluid to stand until quite cold. The
shaking must then be renewed for some time, and the bottle (a
Winchester quart bottle) filled up with water.
Allowthe precipitate to settle for a day, and draw off the clear
supernatant fluid with a syphon. Repeat the washing until
the clear liquid gives little or no precipitate with chloride of
I barium. So much water must be left with the colour at last
I that it shall measure forty fluid ounces.
For the injecting fluid take twenty-four ounces of the
coloured liquid and three ounces of gelatin. Allow them to
remain together twelve hours and dissolve over a water-bath.
Strain through fine muslin.
This formula is the outcome of experiments made to find a
I transparent mass free from    all tendency to extravasation.
The authors consider they have succeeded.
1 Davies, ' On Preparing and Mounting Microscopic Objects,' p. 138.