qj~~ ________

PURPURIN

83

CHAPTER X.
PURPURIN, INDIGO-CARMINE, SAFFRON, ORCHELLA, INK.
98. Purpurin. I-Purp-urin was -first introduced to histo-
RO logical practice by Ranvier, who found in it an important aid
atto the study of cartilage. It is a colouring matter extracted
Of from garance, and is obtained in the form of a pulverulent
body in a state of starch-like agglomeration. It is soluble in
)I a boiling aqueous solution of alum, from which it normally
IAd precipitates on cooling, but may be prevented from so doing
Th  by the addition of a certain proportion of alcohol. The
411tfor ,employment of an alum solution as vehicle for the colourin g
15 matter has the advantage, at least so far as cartilage is con-
cerned, of fixing the cellular elements at the same time that
1'  i8 'they are stained. ( Ranvier found that alum in a solution of
vraq i5-1000 was the best of all fixing agents for cartilage- cells,
'Traiti',' p. 279.)
Apsit 99. Alum Purpurin Staining Solution (Ranvier's formula).
-200 grammes of water and 1 of alum are boiled in a porce-
Ipelain capsule; purpurin rubbed up in -water is added, and the
ind m   boiling continued. The purpurin being dissolved to satura-
tion (this is ensured by taking care to have an unclissolved
excess in the capsule), the solution is filtered hot into a flask
containing 60 c.c. of alcohol (36' Cartier).
There is thus obtained a solution of an ora-nge-rose colour,
presenting a marked degree of fluorescence.
S'Archives de Physiologie,' 1874, p. 761. 'Traiti Technique,' p. 280.
'Traitei Technique,' p. 280.
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PURPURIN, ~~         ~         ~        ~        M ANIOCRIE  OAFRNROCELA IK