IODINE H^EMATOXYLIN. 125 



and expose to the air in a shallow dish for twenty-four hours ; 

 make up the volume to 40 c.c. with proof spirit (warming if 

 necessary to dissolve any separated crystals), and add ammonia 

 alum, 2 grms., dissolved in distilled water, 80 c.c. ; glycerin, 

 100 c.c. ; rectified spirit, 80 c.c.; glacial acetic acid, 10 c.c. 

 This solution requires no ' ripening/ and is ready to be 

 diluted for use (110)." 



This ha3matoxylin is the one most recommended by Squire 

 after extensive experimentation. I regret that up to the 

 present I have not had time to make a trial of it, but have no 

 doubt that it is excellent. Critically examined it is seen to 

 correspond to Mayer's acid haemalum, with the addition of 

 alcohol and glycerin. I apprehend that the formula was 

 arrived at without knowledge of Mayer's work on the subject, 

 in which case the agreement between the two experimenters 

 is very satisfactory. I am doubtful as to the advisability of 

 the addition of alcohol and glycerin to alum-haBmatein solu- 

 tions. I suppose they help to make them keep, but do they 

 not impair the quality of the stain ? 



189. Benaut's Glycerin Hsematoxylm ("Glycerine Hema- 

 toxylique ; " Arch, de PhysioL, 1881, p. 640). Make a satu- 

 rated solution of alum in strong glycerin. Add drop by drop 

 about a quarter of a volume of concentrated solution of haema- 

 toxylin in alcohol. (If you add an excess of hsematoxylin the 

 liquid will become turbid, and you must then add more solu- 

 tion of alum in glycerin until the turbidity disappears.) 

 Filter, and leave the solution exposed to the light and air for 

 some weeks, until it can be perceived by the smell that it no 

 longer contains any alcohol. Filter. 



Sections are stained in this solution in a few minutes. But 

 it can be used in another way, which is an original and really 

 valuable method. If sections or other objects be mounted 

 in a drop of the solution, they will, after a few weeks, be found 

 stained and the glycerin decoloured. Such objects keep the 

 stain for years. 



190. Iodine Haematoxylin (CuccATi, Zeit. f. iviss. Hik., v, 1, 

 1888, p. 55). Dissolve 25 grammes of chemically pure potassic 

 iodide in 25 c.c. of distilled water. Pour this solution gradu- 

 ally and with constant agitation into 75 c.c. of absolute alcohol 



