294 COREOSION, DEOALCIFJCATION, AND BLEACHING. 



take longer, and may require, if time be an object, a solution 

 made with 35 to 45 per cent, of nitric acid. Wash out for 

 two days in running water. The tissues stain well. 



The solution may be made with hydrochloric acid instead 

 of nitric acid, 30 per cent, of acid being taken, and 0*5 per 

 cent, of sodium chloride added. 



For slow decalcification a 2 to 5 per cent, nitric acid solu- 

 tion may be used, or a mixture containing of phloroglucin 

 1 part, nitric acid 5, alcohol 70, and distilled water, 30 parts. 

 -. For the labyrinth, FEEEEEI advises a mixture containing 

 1 grm. of phloroglucin, 10 grms. of hydrochloric acid, 100 of 

 water, and 200 of 70 per cent, alcohol, to be changed once a 

 week during thirty to forty days. 



563. Hydrochloric Acid (see above, 559). RANVIER says that it 

 may be taken of 50 per cent, strength, and then has a very rapid action. To 

 counteract the swelling action o the acid, sodium chloride may be added. 

 Two formulae of this sort have been given by VON EBNEB (see HAUG'S paper 

 quoted in the last section). The first is, 100 c.c. cold saturated solution of 

 sodium chloride in water, 100 c.c. water, and 4 c.c. hydrochloric acid. Pre- 

 parations to be placed in this, and 1 to 2 c.c. of hydrochloric acid added daily 

 until they are soft. The second is, 2'5 parts of hydrochloric acid, 500 of 

 alcohol, 100 of water, and 2'5 of sodium chloride. HAUG prefers the pro- 

 portions of 1*0 to 5'0 of acid, 70 of alcohol, 30 of water, and 0'5 of salt. 



564. Hydrochloric Acid and Chromic Acid (BAYEBL, Arch. f. mik. 

 Anat., 1885, p. 35). Equal partsi of 3 per cent, chromic acid and 1 percent, 

 hydrochloric acid. For ossifying cartilage. HAUG recommends equal parts 

 of 1 per cent, hydrochloric acid and 1 per cent, chromic acid (1. c.). 



565. Hydrochloric Acid and Nitric Acid (HOPEWELL SMITH, Journ. 

 Roy. Hie. Soc., 1892, p. 433). Place teeth in 12 parts of 10 per cent, HC1, 

 and after 15 hours add 1'5 parts of HN0 3 , and after 48 hours add 1*5 parts 

 more of HN0 3 . After 75 to 80 hours remove and wash for half an hour in 

 a solution of 5 grms. of lithium carbonate to an ounce of water. 



566. Hydrochloric Acid and Glycerin. Glycerin, 95 ; hydrochloric 

 acid; 5. Recommended for softening teeth in SQUIRE'S Methods and For- 

 mulse, p. 12. 



567. Picric Acid should be taken saturated. 



Pier o -sulphuric acid should of course be avoided on account of the forma- 

 tion of gypsum. 



Picro-nitric or Pier o -hydrochloric Acid. The reader will perhaps reflect 

 that the last two fluids appear likely to be very useful for decalcifications. 

 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, 



