238 THE MICROSCOPE 



phous mass is then to be powdered. Of this, 15 grains are placed 

 in an ounce of water, to which i fluid drachm of alcohol is added. 

 Sections, after staining, should be washed in alcohol to remove 

 the superfluous colouring fluid, and then transferred to a saturated 

 solution of oxalic acid in alcohol to fix the colour. The oxalic 

 acid is then washed out in alcohol. Finally, the sections are 

 cleared in oil of cloves, and mounted in dammar or Canada 

 balsam in benzole. 



Thiersch's Carmine Fluids. — {a) Red fluid : — Carmine, i 

 part ; caustic ammonia, i part ; distilled water, 3 parts ; this 

 solution is to be filtered. 



A second solution is made as follows : — Oxalic acid, i 

 part; distilled water, 22 parts. One part of the carmine 

 solution is to be mixed with 8 parts of the oxalic acid solu- 

 tion, and 12 parts of absolute alcohol are to be added and 

 filtered. If the filtrate is orange-coloured instead of dark-red, 

 more ammonia is to be added, and the orange becomes red. 

 If crystals of oxalate of ammonia are formed, it must be fil- 

 tered a second time. After staining from one to three minutes, 

 wash in alcohol of about 80 per cent. When the colour has 

 become too dark or difl'usC;, the preparation is to be washed out 

 with an alcoholic solution of oxalic acid. 



{b) Lilac Carmine Fluid. — Borax, 4 parts; distilled water, 56 

 parts ; dissolve and add carmine i part. The red solution is 

 to be mixed with twice its volume of absolute alcohol and filtered. 

 Carmine and borax remain on the filter ; the precipitate, when 

 dissolved in water, may be again used. This fluid is especially 

 useful for cartilage and bones which have been decalcified by 

 chromic acid. 



Alum Carmine. — Take a i to 5 per cent, solution of ordinary 

 alum, or ammonia alum ; boil with J to i per cent, powdered 

 carmine for twenty minutes. Filter, and add a little carbolic acid 

 to preserve it. This is a useful solution, and is recommended by 

 Grenadier. 



Acid Carmine. — An ordinary ammoniacal solution of carmine 

 is to be mixed with acetic acid in excess, and filtered. The red 

 solution thus obtained stains diffusely, but after the addition of 



