.,., MANUAL OF HISTOLOGY. 



in this way. It is therefore desirable, after using the acid, to 

 wash thoroughly in alcohol or water. 



'liurax carmine (Arnold's formula).-The following method 

 is given by Dr M. N. Miller as the one in use by students m 

 the historical laboratory of the New York University, 

 originated with Prof. J. W. S. Arnold. A saturated solution 

 ,f borax is prepared in a wide-mouthed pint bottle. The borax 

 should be in some excess. - "No. 40" carmine is now added 

 to the solution under constant agitation, until after a whili 

 no longer dissolves, and an excess remains at the bottom of the 

 vial, mingled with the crystals of borax. After twenty-four 

 hours the supernatant fluid is decanted. To this clear portion 

 f. ij. of alcohol are added, and f. 3 j. of caustic soda solution 

 (U. S. P.). The staining solution is now ready. Or, the alco- 

 hol may be omitted (Arnold), and the liquid evaporated to dry- 

 ness ; the red amorphous mass is then powdered. Of this, 

 15 grains are placed in an ounce of water, to which f . 3 j. of 

 alcohol is added. 1 



Sections, after staining, should be washed in alcohol to re- 

 move the superfluous coloring fluid, and then transferred to a 

 saturated solution of oxalic acid in alcohol to fix the color. 

 The oxalic acid is then washed out in alcohol ; finally the sec- 

 tions are cleared up in oil of cloves, and mounted in balsam or 

 dammar. 



Double staining by borax carmine and indigo* carmine. 

 Drs. W. T. Norris and E. O. Shakespeare, of Philadelphia, 

 have recommended a method which is a modification of Mer- 

 kel's. Two staining fluids are made, one red and the other 

 blue. The red one contains carmine, gr. 7 ; borax, 3 ss. ; dis- 

 tilled water, j. The blue contains indigo carmine, 3 ss. ; bo- 

 rax, 3ss.; and distilled water, vij. 



After thorough trituration the ingredients are mixed and 

 left in a vessel ; the supernatant fluid is then poured off. The 

 sections, if previously hardened in bichromate, picric acid, or 

 chromic acid, should be well washed ; they then are to be 

 placed for a few minutes in a mixture (equal parts) of the red 

 and blue fluids, then transferred, without washing, to a satura- 

 ted solution of oxalic acid and allowed to remain in it rather 

 less time than in the staining fluid. When sufficiently bleached 



1 [This preparation of borax carmine is the best that I have ever used. T. E. S.] 



