GLYCERIN. ALUM CARMINE. 251 



533. Nitric Acid and Alcohol. 3 per cent, of nitric acid_in_ 

 70 per cent, alcohol. Soak specimens for several days or 

 weeks. I do not know who first recommended this admir- 

 able medium. 



534. Chromic Acid is employed in strengths of from O'l 

 per cent, to 1 per cent., the maceration lasting two or three 

 weeks (in the case of bone) . It is better to take the acid weak 

 at first, and increase the strength gradually. 



535. Chromic and Nitric Acid. Dissolve 15 gr. pure chromic 

 acid in 7 oz. of distilled water, to which 30 minims of nitric 

 acid are afterwards to be added. Macerate for three or four 

 weeks, changing the fluid frequently (Marsh) . 



FOL takes 70 volumes of 1 per cent, chromic acid, 3 of nitric 

 acid, and 200 of water (Lehrb., p. 112). 



536. Hydrochloric Acid may be taken of 50 per cent, strength, 

 and then has a very rapid action (Ranvier) . 



537. Hydrochloric Acid and Chromic Acid (BAYEEL, Arch. f. 

 mik. Anat., 1885, p. 35). Equal parts of 3 per cent, chromic 

 acid and 1 per cent, hydrochloric acid. For ossifying carti- 

 lage. 



538. Picric Acid should be taken saturated. 

 Picro-sulphuric acid should of course be avoided on account 



of the formation of gypsum. 



Picro-nitric or Picro-hydrochloric acid. The reader will 

 perhaps reflect that the two last fluids appear likely to be 

 very useful for decalcitications. Mayer points out that the 

 action is very rapid, and that the copiously evolved C0 2 often 

 produces, mechanically, lesions in tissues; so that in many 

 cases in which calcareous structures are concerned chromic 

 acid is to be preferred, the more so as it more effectually 

 hinders any collapsing of the structures that might result from 

 the withdrawal of their supporting calcareous elements. 



539. Glycerin. Alum-Carmine. It should be remembered 

 that these commonly used reagents dissolve carbonate of lime ; 

 they must therefore be avoided in the preparation of struc- 

 tures containing calcareous elements that it is wished to pre- 

 serve (calcareous sponges, echinodermata, &c.). 



