, CLEARING AGENTS. 81 



the rapidity of evaporation being in the ratio of 4, 5, 

 and 9. 



It is curious that, in two excellent books on this subject, 

 Xylol is described as being more volatile than Benzol in one 

 of them, and Toluol in the other. 



Benzol has also been described as a solvent of the aniline 

 dyes. 



All three are practically without solvent action upon aniline 

 colours. 



OIL OF CEDAR WOOD. 



Although an essential oil it resembles the type Xylol, but 

 evaporates slowly and not to dryness. 



It has very little solvent action on the aniline colours. It 

 clears rapidly from Absolute Alcohol, but not well from 

 90 p. c. Alcohol. Sections can be left in it for several days 

 without becoming brittle. It is a convenient medium in which 

 to examine tissues before mounting them permanently. 



It clears Celloidin without dissolving it. 



OIL OF ORIGANUM. 



This is Oil of White Thyme more or less adulterated ; it 

 dissolves the aniline colours to about the same extent as Oil 

 of Cloves. Another oil, probably Oil of Marjoram, is sold as 

 Oleum Origani Cretici, but this also dissolves the aniline 

 colours. 



BEFORE MOUNTING IN GLYCERINE. 



Liquid Carbolic Acid, Liquor Potassae, Alcoholic Solution 

 Potash, Liquor Ammonise, Solution of Chloral Hydrate, Eau 

 de Javelle, Eau de Labarraque, are all used for clearing 



G 



