280 CHAPTER XXTV. 



555. Decalcification of Bone. — I take the following from 

 BtJSCH, Arch. mik. Anat., xiv, 1877, p. 481 ; see also Haug, 

 in Zeit. wiss. Milt., viii, 1891, p. 1 ; and Schaffeb, ibid., xix, 

 1903, pp. 308 and 441, and his paper in the Encycl. mik. 

 Technik. 



The most widely used, though not the best, agent for 

 decalcification is hydroMoric acid. Its action is rapid, 

 even when every dilute, but cavises serious swelling of the 

 tissues. To remedy this, chromic acid or alcohol may be 

 added to it. Or a 3 per cent, solution of the acid may 

 be taken and have dissolved in it 10 to 15 per cent, of 

 common salt. Or (Waldeyer) to a yyVo" P^^ cent, solution 

 of chloride of 'palladium may be added j\ of its volume of 

 HCl. 



Chromic acid is also much used, but has a very weak de- 

 calcifying action and a strong shrinking action on tissues. 

 For this reason it should never be used in solutions of more 

 than 1 per cent, strength, and for delicate structures much 

 lower strengths must be taken. 



ThoKjihoric acid has been recommended for young bones. 



Acetic, lactic and i^yroligneous acids have considerable 

 decalcifying power, but cause great swelling. Picric acid 

 has a very slow action, and is only suitable for very small 

 structures. 



556. Nitric Acid (Busch, loc. cit.). — To all other agents 

 BuscH prefers nitric acid, which causes no swelling and acts 

 most efficaciously. 



One volume of chemically pure nitric acid of sp. gr. 1'25 

 is diluted with 10 vols, water. It may be used of this 

 strength for very large and tough bones j for young bones it 

 may be diluted down to 1 per cent. 



Fresh bones are first laid for three daj^s in 95 per cent, 

 alcohol; they are then placed in the nitric acid, which i^ 

 changed daily, for eight or ten days. They must be removed 

 as soon as the decalcification is complete, or else they will 

 become stained yello^v. When removed they are washed 

 for one or two hours in running water and placed in 95 per 

 cent, alcohol. This is changed after a few days for fresh 

 alcohol. 



Young and foital bones may be placed in the first instance 



