DECALCIFYING FLUIDS. 37 



saturated and ke^t saturated. This is done by keeping some 

 crystals of picric acid in the bottom of the bottle. There must be 

 a large volume of fluid, and the bone should be suspended in the 

 fluid. It usually requires a fortnight to decalcify a small bone. 

 Picric acid acts as a fixing, hardening, and staining reagent. 



After the bone is decalcified it should be washed and kept in 

 spirit not water until no more yellow stain is given up to the 

 alcohol. This rule, however, is not rigidly followed. 



5. v. Ebner's Fluid. This fluid prevents the ground substance 

 of bone from swelling up. Sections should be examined in 10 per 

 cent, solution of sodic chloride, if it be desired to see the fibrillar 

 structure of bone, but sections of bone softened in this way may be 

 mounted in other media, if it be desired to see the other details 

 in the structure of bone. (See Bone.) It has the following com- 

 position : 



Alcohol ..... 500 cc. 



Water ...... 100 ,, 



Sodic chloride . . . . 2.5 grams. 



Hydrochloric acid . . . . 2.5 cc. 



6. Picro-Sulphuric Acid or Picro-Nitric Acid (p. 3 1 ). 



7. Arsenic Acid. I find that a 4 per cent, solution of this acid 

 rapidly decalcifies a bone at 30 to 40 C. The tissues, after harden- 

 ing in alcohol, are well preserved and stain readily. 



8. Chromo-Osmic Acid (Haug). 



Osmic acid (i per cent.) . . .10 cc. 



Chromic acid ( i per cent. ) . . . 25 ,, 



Water .... . 65 



Very useful for delicate tissues, e.g., very young developing teeth. 

 Wash in water and harden in 70 per cent, alcohol. 



9. Phloroglucin Method. Dissolve with the aid of gentle heat 

 i gram of phloroglucin in 10 cc. pure non-fuming nitric acid. To 

 the red fluid add 100 cc. of 10 per cent, watery solution of nitric 

 acid. The following mixture acts more slowly : 



Phloroglucin ..... I gram. 



Nitric acid . . . . 5 cc. 



Alcohol . . . . . 70 ,, 



Water . . 30 ;, 



Phloroglucin itself does not decalcify, it only protects the tissues 

 from the action of the nitric acid. By this method dccalcification 

 ran be done very rapidly, even in a few hours. 1 find that a portion 

 of a human clavicle about an inch in length is softened in 12-16 

 hours, the outer surface being stained slightly red. 



Methods. The bone should be cut into short pieces and placed 



