16 THE VICTORIAN NATURALIST. 



of this kind, in teaching a class of biology, that induced me to tura 

 my attention to the subject. 



Methols of dry preservation of the soft parts of animals are known 

 to some museum keepers and others, but they are, as a rule, too 

 complicated and troublesome for ordinary use. Compared with 

 the method I am about to give, they remind one of the system of 

 dosing the living body, in vogue not so long ago, making up iu 

 quantity and complexity of ingredients, for any possible lack of 

 quidity. As an example, I will just give one such method, received 

 from a medical gentleman in Edinburgh, and used with good effect. 

 The fluid is prepared by dissolving in 3000 grammes boiling water, 

 100 of Alum. 

 25 of Common Salt. 

 12 of Nitrate of Potash. 

 60 of Carbonate of Potash. 

 80 of Arsenious Acid, 

 tlien cool and filter. 



To every 10 litres of solution, add 



4 litres of Glycerine, and 

 1 litre of Methylated Spirit. 

 Such is the fluid, consisting of 7 different substances, and the pre- 

 parations to be preserved dry, are immersed in it from 6 to 12 days, 

 and then dried in the open air. Hollow organs to be filled witli it 

 before immersion, afterwards inflated with air and dried. It was 

 perfectly plain to me that a complicated process like this could never 

 And general acceptance, and that some simpler fluid, for fluid 

 apparently it must be, was requisite. 



In my first attempts, a number of different substances were tried, 

 but without success. Thus glycerine-jelly, a well-known preservative, 

 was used for the first course, then alcohol to remove water and harden. 

 Soaking iu melted paraffin was next tried, expecting it so to 

 permeate tlie specimen as to dry without shrinking. Steeping in. 

 gum was a third process, then hardening the gum by means of 

 alcohol, which removes the water. But all the specimens proved 

 unsuccessful on attempting to dry them. 



My most promising attempt was made when I tried a solution of 

 chromic acid, a commonly used hardening agent, with alcohol 

 afterwards to remove the water. Theoretically, this simple process 

 should have been a success, for. after fixing and hardening the 

 specimen with the acid, and removing excess, as well as water 

 by moans of alcohol, what was there to prevent it drying and becoming 

 pern\ancntly preserved? But again my rising hopes were doomed 

 to disappointment, for practically, it turned out that on drying, the 

 specimens shrank and shrivelled up. Everything promised tair till 

 the drying commenced, and how to prevent shrinking was the 

 problem I had now to solve. Fortunately, just at this juncture, 

 I happened to read a short paragraph in the journal of the Royal 



