126 H2EMATEIN AND OTHER ORGANIC STAINS. 



contained in a stoppered bottle. Close the bottle thoroughly. 

 Rub up in a mortar 75 eg. of crystallised hgematoxylin with 

 6 grammes of chemically pure roche alum,* and add 3 c.c. of 

 the iodine solution. Keep the mixture agitated, and add gra- 

 dually the rest of the iodine solution ; then replace the whole 

 in a well-stoppered bottle. Agitate for some time, in order to 

 get the alum to dissolve, and let stand for ten to fifteen hours. 

 Then shake well and filter, taking the usual precautions 

 against evaporation of the alcohol, and preserve in a well- 

 stoppered bottle. 



Objects should be left in the liquid for ten hours, then 

 well washed in water and mounted in glycerin, or washed in 

 alcohol and mounted in balsam. 



The solution is stated to be perfectly stable and to give a 

 pure chromatin stain, and to be well adapted for staining in 

 the mass, as it never over-stains. 



191. Iodine Hsematoxylin (SANPELICE, Journ. de Microgr., 

 xiii, 1889, p. 335; Journ. Roy. Mic. Soc., 1889, p. 837). 

 Dissolve O70 grm. haematoxylin in 20 grms. absolute alcohol, 

 and 0*20 grm. alum in 60 c.c. distilled water. Add the first 

 solution, drop by drop, to the second. Expose the mixture to 

 the light for three or four days, add ten to fifteen drops of 

 tincture of iodine, agitate, and allow to stand for some days. 

 Stain for twelve to twenty-four hours, and wash out for the 

 same time in 90 per cent, alcohol, acidulated with acetic 

 acid. The fluid keeps well. 



Mayer (Mitth. Zool. 8tat. Neapel, 10, 1, 1891, pp. 178, 

 182) remarks on this that it is essentially aBohmer's solution 

 with somewhat more alcohol, and stains well when ripe, the 

 function of the iodine being to prevent the formation of pre- 

 cipitates of colouring matter on the surface of the objects, 

 and not to directly increase the penetrating power of the 

 stain. 



192. Other Aqueous Alum-Hsematoxylins. ABNOLD, see Quart. 

 Journ. Mic. Sci., 1878, p. 86. MITCHELL, see Journ. Roy. Mic. Soc., 1884, 



* Koche alum, or Eoman alum (allume di rocca, alun de roche, alumen 

 rubrum verum, and other synonyms), is an alum originally imported from 

 Civita Vecchia, and much esteemed by dyers from being nearly free from 

 iron-alum. That now sold for it in England is ordinary alum coloured with 

 Venetian red, Armenian bole, or rose-pink (alumen rubrum spurium). See 

 COOLEY'S Cyclopaedia of Pract. Receipts, s. v. " Alum, Roman." 



