44 CHAPTER IV. 



57. Bichromate and Sublimate (KULTSCHITZKY, Arch./, mik. Anat., 

 xlix, 1897, p. 8). Two parts bichromate, part corrosive sublimate, 

 50 parts 2 per cent, acetic acid, and 50 parts 96 per cent, alcohol. The 

 mixture should be filtered after twenty-four hours. Tissues of verte- 

 brates may remain in it for four to six days. LAVDOWSKY -(Zeit. iviss. 

 Mik., xvii, 1900, p. 301), takes 500 c.c. of 1 per cent, acetic acid, 20 to 25 

 g. bichromate, and 5 to 10 c.c. saturated solution of sublimate in water. 



58. Bichromate of Ammonia. This salt is in considerable favour 

 for hardening. Its action is very similar to that of the potassium salt. 

 Fol says that it penetrates somewhat more rapidly, and hardens some- 

 what more slowly. It should be employed in somewhat stronger solu- 

 tions, up to 5 per cent. 



59. Neutral Chromate of Ammonia is preferred by some. It is used 

 in the same strength as the bichromate. Klein has recommended it for 

 intestine, which it hardens, in 5 per cent, solution, in twenty-four hours. 



60. Bichromate of Calcium. SONNENBRODT (Arch. mikr. Anat., 

 Ixxii, 1908, p. 416), fixes ovaries of Gallus in 20 parts of 2 per cent, 

 sol. of calcium bichromate with 10 of 2 per cent. sol. of sublimate and 

 1 of acetic acid. 



61. Bichromates and Alcohol. Mixtures of bichromate of potash 

 or ammonia with alcohol may be employed, and have a more rapid action 

 than the aqueous solution. Thus HAMILTON takes for hardening brain 

 a mixture of 1 part methylated spirits with three parts of solution of 

 Miiller ; see also KULTSCHITZKY'S Mixture, ante, 55). Preparations 

 should be kept in the dark during the process of hardening in these 

 mixtures. 



62. Sulphurous Acid. WADDINGTON (Journ. Roy. Mic. Soc., 1883, 

 p. 185) uses a saturated solution of sulphurous acid in alcohol for fixing 

 infusoria. OVERTON (Zeit. wiss. Mik., vii, 1890, p. 9) uses the vapours 

 of an aqueous solution for fixing alga?. 



