DEOALCIFICATJON, PESlLICIFICATION, AND BLEACHING. 283 



566. Picric Acid should be taken saturated and changed frequently. 

 Its action is weak, but it gives good results with small objects. 



Picro-nitric or Picro-hydrochloric Acid. Action very rapid. 



567. Phosphoric Acid. 10 to 15 per cent. (HAUG, loc. cit. in 555). 

 Somewhat slow, staining not good. According to SCHAFFER, 557, it 

 produces swelling. 



568. Lactic Acid. 10 per cent, or more. Fairly rapid, preserves 

 well, and may be recommended (HAUG, loc. cit.). 



569. Chromic Acid is employed in strengths of from O'l per cent, to 

 2 per cent, (but see 555), 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. Action excessively slow. 



570. Chromic and Nitric Acid. SEILER (FoL, Lehrb., p. 112) takes 

 70 volumes of 1 per cent, chromic acid, 3 of nitric acid, and 200 of water. 

 The action is still excessively slow, frequently requiring months to be 

 complete. 



571. Chromo-aceto osmic Acid (VAN VER STRICHT, Arch. BioL, 

 ix, 1889, p. 29; and SCHAFFER, Zeit. wiss. Mik., x, 1893, 

 p. 179). Objects to be left in it for months, the liquid being 

 changed at first every two days, afterwards less frequently. 

 Structure well preserved. 



572. Arsenic Acid. 4 per cent, aqueous solution, used at a tempera- 

 ture of 30 to 40 C. (SQUIRE'S Methods and Formulx, etc., p. 11). 



573. Phloroglucin with Acids (ANDEER, Centralb. med. Wiss., 

 xii, xxxiii, pp. 193, 579 ; Intern. Monatsschr., i, p. 350 ; HAUG, Zeit. 

 wiss. Mik., viii, 1891, p. 8; FERRERI, ibid., ix, 1892, p. 236; Bull. R. 

 A'-cad. Med. di Boma, 1892, p. G7). This is said to be the most rapid 

 method of any. Phloroglucin by itself is not a solvent of lime salts ; 

 its function in the mixture given below is so to protect the organic 

 elements of tissues against the action of the mineral acid that this can 

 l)e used in a much more concentrated form than would be otherwise 

 advisable. 



ANDEER takes a saturated solution in warm water, and adds to it 5 to 

 50 per cent, of hydrochloric acid. Wash out in running water. 



Other acids than hydrochloric may, of course, be taken. See HAUG, 

 Zeit. wiss. Mik., viii, 1891, p. 8, and FERRERI, Bull. Ac/id. Med. Roma, 

 1892, p. 67, or (for both) fifth edition. 



Desilicification. 



574. Hydrofluoric Acid (MAYER, Zool. Auz., 1881, p. 593). 

 The objects are brought -in alcohol into a glass vessel coated 



