DECALCIFYING FLUIDS. 13 



days, then treated with the Nitric Acid solution, which is 

 changed daily for about a week ; as soon as decalcification 

 is complete, wash thoroughly in Water, and place in 70 p. c. 

 Alcohol. 



(vii.) NITRIC ACID AND CHROMIC ACID. 



Chromic Acid, 1 grm. ; Water, 200 cc. ; Nitric Acid 3 cc. 



This is one of the best softening fluids for general use, the 

 Chromic Acid hardening the bone protoplasm, while the Nitric 

 Acid dissolves out the calcareous salts. 



It takes about a fortnight, and the solution must be renewed 

 every third day. The tissue is then well washed in water and 

 transferred first to weak and then to strong Alcohol. 



(viii.) PICRIC ACID. 



A saturated aqueous solution. Useful for softening foetal 

 bone. The tissue should be suspended in twenty times its 

 bulk of fluid, which must be kept saturated with crystals 

 of Picric Acid. It takes about a month; the tissue when 

 softened must be first well washed in Water and then passed 

 from weak into strong Alcohol (see " Alcohol"). 



