256 DECALCIFICATION, DESILICIFICATION, ETC. 



material that has been blackened by osmic acid, and, according to 

 renewed experiments of MAYER'S, is to be preferred to the peroxide 

 of hydrogen method. 



For bleaching chitin of insects, not alcohol but water should be 

 added to the chlorate and acid (MAYER), Arch. Anat. PJiys., 1874, 

 p. 321). 



See also MAYER in Zeit. wiss. Mik., xxiv, 1907, p. 353 (paraffin sections 

 exposed to the vapour of chlorine water). 



GRYNFELTT and MESTREZAT (G. E. Soc. Biol., Ixi, 1906, p. 87) add 

 2 c.c. of 20 per cent, solution of chloric acid (HC10 ; .) to 15 c.c. of alcohol 

 and put sections (of retina) into it for several hours at 42 C. 



568. Eau de Labarraque. Eau de Javelle (see 544, 545). These 

 are bleaching agents. For the manner of preparing a similar solution 

 see early editions, or Journ. de Microgr., 1887, p. 154, or Journ. Hoy. Mic. 

 Soc., 1887, p. 518. Of course, the method cannot be used for bleaching 

 soft parts which it is desired to preserve. 



569. Peroxide of Hydrogen (Oxygenated Water) (POUCHET'S 

 method, M. DUVAL, Precis, etc., p. 234). Macerate in glycerin, to 

 which has been added a little oxygenated water ( 35), 5 to 6 drops 

 to a watch-glass of glycerin. SOLGER (Centralbl. med. Wiss., xxi, 

 1883, p. 177) takes a 3 per cent, solution of peroxide. FURST 

 (Morph. Arb. Schwalbe, vi, 1896, p. 529) points out that after a time 

 it macerates. 



The method serves both for removing pigments and for bleaching 

 osmic and chromic material. 



570. Peroxide of Sodium (CARAZZI, Zool. Anz., 444, 1894, p. 135). 



See previous editions. 



571. Peroxide of Magnesium (MAYER, Grundsuge, p. 290). Use as 

 chlorine, 567. A slow but delicate method. 



572. Sulphurous Acid. Prof. GILSON writes me that he finds 

 alcoholic solution of sulphurous anhydride (S0 2 ) very convenient 

 for the rapid decoloration of bichromate objects. A few drops suffice. 

 MONCKEBERG and BETHE (Arch. mik. Anat., liv, 1899, p. 135) 

 obtain the acid by adding to 10 c.c. of a 2 per cent, solution of 

 bisulphate of sodium 2 to 4 drops of concentrated hydrochloric acid. 

 Objects are put into the freshly prepared solution for six to twelve 

 hours. 



573. Permanganate of Potash. ALFIERI (Monitore Zool. Ital., viii, 

 1897, p. 57) bleaches celloidin sections of the choroid, etc., for eight to 

 twenty-four hours in a 1 : 2000 solution of permanganate of potash, then 

 washes them out for a few hours in a solution of oxalic acid of 1 ; 300 

 strength, or weaker. 



