30 MICROSCOPY. 



CHAPTEE III. 

 REAGENTS AND STAINS. 



In preparing the following reagents it is well to remember that 

 the weight of a cubic centimeter of water is one gram, and that a 

 liter contains 1,000 cubic centimeters. The formulae that are given 

 are those most commonly used and are briefly stated : 



NORMAL FLUIDS. 



Distilled water. A supply of distilled water should be constantly 

 at hand for the preparation of the reagents and stains. 



Normal saline. This is prepared by dissolving one part, by 

 weight, of sodium chloride in 150 parts of distilled water. 



MACERATING FLUIDS, 



Dilute alcohol. This may be prepared by mixing one part of 

 ninety-live per cent alcohol with two parts of distilled water. Other 

 fluids used for this purpose are solutions of potassium bi-chromate, 

 two per cent, and caustic potash, twenty-five per cent. 



DECALCIFYING FLUIDS. 



Picric acid. Make a saturated aqueous solution of picric acid. 

 This is an excellent fluid for decalcifying bones, serving at the same 

 time as a staining reagent. Crystals should be added from time to 

 time, so that some undissolved crystals will always remain in the 

 bottom of the vessel. 



Nitric acid. Use a ten per cent volumetric solution in water. 

 Decalcification occurs in five to ten days. 



FIXING REAGENTS. 



Absolute alcohol. Specimens should remain in this reagent from 

 one to six hours, according to size. 



Perenyi's fluid 



Nitric acid (ten per cent) 40 cc. 



Chromic acid (0.5 per cent) 30 cc. 



Alcohol . . . 30 cc. 



