MAYER'S H^IMACALCIUM. 119 



however, require twenty-four hours' staining, and should be 

 washed out for the same time (this should be done with 1 per 

 cent, alum- solution if a sharp nuclear stain be desired). 



Mayer's preparations have kept well in glycerin (care 

 being taken not to have it acid), also in balsam. It is to be 

 noted that if oil of bergamot be used for clearing, it must be 

 thoroughly removed by means of oil of turpentine befoFe 

 mounting ; and that oil of cloves is dangerous. 



Haemalum may be mixed with alum-carmine, Saurefuchsin, 

 or the like, to make a double-staining mixture ; but it seems 

 preferable to use the solutions in succession. 



181. MAYER'S Acid Haemalum (ibid., p. 174, note). This 

 is haemalum with 2 per cent, glacial acetic acid (or 4 per 

 cent, common acetic acid). To be used as the last, wash- 

 ing out with ordinary water in order to obtain a blue- 

 violet tint of stain. It has the advantage of being a perhaps 

 even more precise nuclear stain than the last formula ; and 

 further, the solution does not precipitate through decompo- 

 sition caused by the ammonia of the air and the alkali of 

 the glass of bottles, which the simple hsemalum solution does 

 to a certain extent (though this does not affect its staining 

 power). 



182. MAYER'S Hsemacalcium (ibid., p. 182). Hasmatein (or 

 its ammonia-salt), 1 grm.; chloride of aluminium, 1 grm. ; 

 chloride of calcium, 50 grms. ; glacial acetic acid, 10 c.c. (or 

 common acetic acid, 20 c.c.) ; 70 per cent, alcohol, 600 c.c. 

 Eub up finely together the first two ingredients, add the 

 acid and alcohol, dissolve either cold or with heat ; lastly add 

 the chloride of calcium. 



A reddish-violet liquid, imagined as a substitute for KLEIN- 

 ENBERG'S solution, in view of the many disadvantages of the 

 latter (see below, 184). To be used in the main as Kleinen- 

 berg's. If the objects stain in too red a tone they should be 

 treated with a solution (of about 2 per cent.) of chloride of 

 aluminium in alcohol, or with a 0'5 to 1 per cent, solution of 

 acetate of soda or potash in absolute alcohol, or with bicar- 

 bonate of soda (see above, 178). 



The solution is not perfectly stable, but in course of time 

 (Mitth. a. d. Zool. Stat. Neapel, 10, 3, 1892, p. 499) turns 

 blue and precipitates. To avoid this the mixture should be 



