56 Iinw TO WORK 



BO2. Solution of Naphtha anil Creosote:-- 



Creosote 3 drachms. 



Wood naphtha ... 6 oumx-.s. 



Distilled water ... 64 ounces. 



Chalk, as much as may be necessary. 



Mix first the naphtha and creosote, then add as much prepared 

 chalk as may be sufficient to form a thick smooth paste ; afterwards 

 add, very gradually, a small quantity of the water, which must be 

 well mixed with the other ingredients in a mortar. Add two or 

 three small lumps of camphor, and allow the mixture to stand in a 

 lightly covered vessel for a fortnight or three weeks, with occasional 

 stirring. The almost clear supernatant fluid may then be poured off 

 and filtered if necessary. It should be kept in well-corked or stop- 

 pered bottles. 



I have some large preparations which have been preserved in 

 upwards of a pint of this fluid, for nearly twenty years, and the fluid 

 is now perfectly clear and colourless. Some dissections of the 

 nervous systems of insects have kept excellently ; the nerves retain 

 their white appearance, and have not become at all brittle. Two or 

 three morbid specimens are also in an excellent state of preservation, 

 the colour being to a great extent preserved, and the soft character oi 

 the texture remaining. I have one preparation mounted in a large 

 gutta-percha cell, containing nearly a gallon of this fluid. 



A solution of wood naphtha or pyroacetic spirit in water, has been 

 recommended by Professor Quekett, and forms an excellent pre- 

 servative solution, in the proportion of one part of the naphtha to 

 ten of water. The solution is often a little cloudy, but may be made 

 quite clear by filtration after the mixture has been allowed to stand 

 still for some days. 



One great advantage of these aqueous preservative solutions is 

 that the natural appearance of the structure is very slightly altered. 

 The solution, however, after a time renders many of the more delicate 

 structures more or less granular. 



103. Carbolic Acid.- A solution of carbolic acid in distilled 

 water also preserves many animal and vegetable preparations exceed- 

 ingly well. The water will only take up a very small quantity, but 

 the preservative properties of the weakest solution are very great. 

 One part of carbolic acid to a hundred of water is sufficient. Carbolic 

 acid may be obtained perfectly pure in a crystalline state of Messrs. 

 Hopkins and Williams, New Cavendish Street. 



104. Solution of Chromic Acid. A solution of chromic acid is 

 well adapted for preserving many microscopical specimens. It is 



