300 APPENDIX 



Tissues are left in this 2 to 6 days, and the hardening 

 completed with alcohol. 



Potassium bichromate and cupric sulphate (Erlicki's 

 fluid). 



Potassium bichromate 2'5grms. 



Cupric sulphate -5 grm. 



Water 100 c.c. 



This is sometimes used for the brain and cord, when a quicker 

 hardening agent than potassium bichromate is required. After 

 two days the tissue with the fluid may be kept at 38 to 40 C. ; 

 it will then be ready in 3 or 4 more days. 



If the sections have a precipitate on them they should be 

 placed in warm water acidulated with hydrochloric acid. 



Potassium bichromate and mercuric chloride. 



1 p.c. acetic acid 500 c.c. 



Potassium bichromate 20 grams. 



Mercuric chloride 5 grams. 



The tissue is left 2 to 3 days in the mixture, and 2 days to 

 a week in strong alcohol. 



This hardening has been recommended for the central nervous 

 system, preliminary to the Weigert medullary stain (acetate of 

 copper, hsematoxylin, etc., cp. p. 245). 



Potassium bichromate and sodium sulphate (Miiller's 



fluid). 



Potassium bichromate 25 grams. 



Sodium sulphate 10 grams. 



Water 1 litre. 



Miiller's fluid and formol. To Miiller's fluid as above add 

 50 to 100 c.c. of formol. The formol should not be added until the 

 fluid is required for use. This mixture may be used to harden 

 organs or large pieces of tissue ; it fixes small pieces of tissue in 

 about a day. 



Miiller's fluid and mercuric chloride (Zenker). 

 Mailer's fluid 100 c.c. 



Mercuric chloride 5 grams. 



When required for use add 5 c.c. of acetic acid. 



