56            THE MICROTOMIST'S VADE-MECUM
Hennequy that good results are obtained by acidulating alum        i
carmine with acetic acid.  (Two or three drops of the acid to
a watch-glass of the carmine solution.)  This method is in use
at the laboratory of Prof. Balbiani.
62. Alum-carmine and Osmic Acid.-In the laboratory of            i
Prof. Biitschli, of Heidelberg, alum-carmine is employed in       t
combination with osmic acid, in the following manner:               ist
To 50 or 60 grammes of water is added alum-carmine until        WgL
the mixture is of an almost red rose colour; about ten drops        I'
of a -2Th solution of osmic acid are then added.    (The mix-
ture should have an appreciable smell of osmic acid.)     The    rwhn
objects to be stained remain in the mixture for about thirty-     fRc
six hours, in the dark.                                           11,iku
Staining is stated to be more precise than with plain alum-     v stalin
carmine.                                                           cnctil
I do not know to whom this plan is due.                         DifRt,5
63. Alum Carmine (Tangl's formulal).-Powdered carmine             l.
boiled in saturated solution of alum for ten minutes and the      ution
solution filtered. tW     2-    w,.-t A
64. General Remarks on Piero-carmine.-Picrb-carmine-             indj1i
stained preparations should be mounted in balsam, or if in         prinl
glycerin this should be acidulated with 1 per cent. of acetic      5teth
or, better, formic acid.                                            as
Picro-carmine is a nuclear stain with a tendency to diffuse      tohat
into formed tissues. If the preparations be washed, after stain-    distill(
ing, with water, it is a single stain, the colour of the carmine     k6
alone appearing; if they be washed quickly in alcohol it is a       thti
double stain, the yellow colouration of the picric acid not being   at pi
dissolved out by the alcohol as it is by water. Of course the       simpe
washing with alcohol must not be overdone or the yellow             as
colouration may be entirely removed.                                us
HCl and Piero-carmine (Neumann's method ofusing2).-Stain          qi
I Pringsheirn's 'Jahrb.,' 1880, t. xii. Carnoy, 'La Biologic Cellulaire,'  IT
p. 92.
2 'Arch. Mik. Anat.,' Bd. xviii (1880), p. 130.


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