ALCOHOLIC BORAX-CARMINE. 107 



alcoholic, therefore more penetrating ; that it has less tendency 

 to form granular precipitates in the interior of objects, and 

 that it keeps perfectly without precipitating. 



169. Alcoholic Borax- Carmine (G-RENACHER, Arch. f. mik. 

 Anat.j xvi, 1879, p. 466, et seq.). Take a concentrated solution 

 of carmine in borax solution (2 to 3 per cent, carmine to 4 per 

 cent, borax) ; dilute it with about an equal volume of 70 per 

 cent, alcohol, allow it to stand some time, and filter. Or the 

 mixture of carmine and borax solution is allowed to stand for 

 two or three days and occasionally stirred ; the greater part of 

 the carmine will dissolve. To the solution is added an equal 

 bulk of 70 per cent, alcohol ; the mixture is allowed to stand 

 for a week, and then is filtered. If on keeping more carmine 

 is deposited, it must be refiltered. 



Preparations should remain in the stain until they are 

 thoroughly penetrated (for days if necessary), and then be 

 brought (without first washing out) into alcohol acidulated 

 with 4 to 6 drops of hydrochloric acid to each 100 c.c. of 

 alcohol. They are left in this until they are thoroughly pene- 

 trated, and may then be washed or hardened in neutral alcohol. 

 Four drops of HC1 is generally enough. Three drops I find 

 not quite sufficient. The stained objects should remain in the 

 acidulated alcohol till they acquire a bright transparent look 

 (three to six hours) . 



For delicate objects, and for very impermeable objects, it 

 may be well to increase the proportion of alcohol in the stain ; 

 it may conveniently be raised to about 70 per cent. The 

 washing out, or decoloration, will be enormously facilitated 

 if picric acid be added to the acidulated alcohol, but in this 

 case the proportion of HC1 should be reduced. It should not 

 exceed that of 1 drop of HC1 to 100 c.c. of alcohol, and the 

 decoloration should be carefully watched, as the stain may 

 easily be entirely washed out in this mixture. For this reason 

 the process is not to be recommended in general; I merely 

 mention it because it is well that the student should be 

 acquainted with the reaction. 



This stain is probably by far the most popular of any for 

 staining in the mass. It is easy to use, and gives a most 

 splendid coloration. But it is not so penetrating as is 

 commonly supposed, and has the defect of sometimes forming 



