THE MICROTOMIST'S VADE-MECUM

83. Alcoholic Carmine (Hoyer's formula,).-Scrapings of         fiz sA
carmine (" sonst nicht weiter zu verwendende Carmiurick-         i;
stiinde ") are thrown into a retort with alcohol acidulated       jutO
with a small percentage of sulphuric acid and kept simmering      iiOst
over a water-bath until the carmine is dissolved. Filter,          Thjs
dilute largely with water, and add solution of sugar of lead     gd e
so long as the rose-coloured precipitate of sulphide of lead      abig
continues to be thrown down. As soon as a violet precipitate       (ios
makes its appearance in the place of the rose-coloured one,        ddWJ
filter, and to the filtrate again add solution of sugar of lead   tiDst
so long as the violet precipitate continues to form. This is     trtds(
now collected on a filter, washed, dried, and suspended in a       g, E
small quantity of strong alcohol. To this is added alcohol,       0Giea
strongly acidulated with sulphuric acid, drop by drop, until       Four
the violet precipitate is seen to have lost its colour and the    lohol
alcohol is become intensely red. Filter, and keep the solution    Ivird
for use. It contains essentially the same colouring matter as      Work
the solutions of carmine in acetic, oxalic, or other acids. Two    sqidl
drops of the solution in a watch-glassful of water make a          au1stic
strongly staining liquid. The author gets better results with      &jesit
it than with Rollett's " Carminroth."                              Ve
84. Alcoholic Carmine (Grenacher's formula2).-To 50 cubic        @si
centimetres of alcohol (60 to 80 per cent.) add 3 to 4 drops       akok
of hydrochloric acid and a knife-pointful of powdered carmine.    SetIo10
Boil for ten minutes. When cool, filter.                            i),
The solution may or may not be now ready for use; this           how
depends on the proportions of acid and carmine used, and
these proportions cannot be exactly prescribed on account of       lof
the variability of commercial carmine. If the solution is
found to give in five or ten minutes a diffuse stain (like a
borax-carmine stain, see No. 76), more hydrochloric acid must
be cautiously added drop by drop, and the solution tested
with fresh sections until the desired effect is produced. If
I ' Arch. Mik. Anat.,' xiii (1876), p. 650.
2 ' Arch. Mik. Anat.,' xvi (1879), p. 468.

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