FIXING AND PRESERVATIVE MEDIUMS 53 



41.— MiiUer's Fluid 



Potassium bichromate (bichromate of potash) . 2-2^ parts or 45 grammes 

 Sodium sulphate (sulphate of soda) . . i part „ 20 „ 



Water . . . . 100 parts ,, 2 litres 



Lee remarks that this does not seem to be so much used 

 of late years, simple bichromate solutions having taken its place, 

 but that the superiority of Miiller's Fluid is not illusory, owing 

 to the formation in it of some proportion of free chromic acid. 



42. — Potassium Bichromate Solution 



Potassium bichromate . . . .5 parts 



Distilled water . . . . • 95 u 



This is stated by Lo Bianco to slowly harden some 

 gelatinous animals without rendering them fragile, which is 

 not the case with chromic acid. The abundant precipitate 

 which it gives, however, when the objects are placed in alcohol 

 is not a recommendation, but probably this may be obviated 

 by after-treatment (see pp. 46, 54, and 55). 



All varieties of Miiller's solution have, as their chief base, 

 the invaluable bichromate of potassa — invaluable, because 

 experience has proved its efiSciency in every manner possible, 

 and in the Leicester Museum it is in daily use for a variety of 

 subjects. In a former work it was noted that two " topers " — 

 dog-iishes of six feet in length — were preserved in bichromate 

 of potassa, the proportions then given being far in excess of 

 what was needed. That was on 13th September 1882 ; one was 

 cast from about two years afterwards, and made a good mould, 

 and the other remains in a tub out of doors to present date, 

 darker in colour, owing to the excess of bichromate, but yet 

 pliable and fresh, and this after a period of more than thirteen 

 years ! A conclusive proof of the value of this salt. 



Since then, several specimens of the rare Dipnoid fish 

 Ceratodus forsteri have reached the Museum from Australia, 



