98 ClI.UTKli VIM. 



the slide (Chapter X), unless it is desired to keep them 

 loose, all that now remains is to get rid of the paraffin and 

 mount or stain as the case may be. Many solvents have 

 been recommended for this purpose : Turpentine, warm 

 turpentine, a mixture of four parts of essence of turpentine 

 with one of creasote, creasote, a mixture of turpentine and oil 

 of cloves, benzin, toluol, xylol, thin solution of Canada balsam 

 in xylol (only applicable to very thin sections), hot absolute 

 alcohol, naphtha, or any other paraffin oil of low boiling- 

 point. Of these xylol and toluol are generally in most 

 respects the best. Benzol and chloroform are too volatile 

 for safe manipulation. 



If the slide be warmed to the melting-point of the paraffin, 

 a few seconds will suffice to remove the paraffin if the slide 

 be plunged into a tube of xylol or toluol. For thin sections, 

 10 to 15 /i, it is not necessary to warm at all. The sections 

 may be mounted direct from the xylol, or the slide may be 

 brought into a tube of alcohol to remove the solvent for 

 staining. 



Paraffin sections can be stained without removal of the paraffin, so 

 that after-treatment with alcohol can be suppressed, but this is only 

 very exceptionally advantageous. 



151. Pure Paraffin It is now almost universally admitted 

 that pure paraffin is superior for ordinary work to any of 

 tin- many mixtures with wax and the like that used to le 

 recommended. Paraffin varies enormously in hardness ac- 

 cording to the temperature of its surroundings. It should 

 therefore be taken of a melting-point suitable to the 

 temperature of the laboratory. A paraffin melting at 50 C. 

 or a little harder, is that which in my experience gives the 

 best results so long as the temperature of the laboratory is 

 between 15 and 17 C. For higher temperatures a harder 

 paraffin is required, and for lower temperatures a softer one. 



Many workers of undoubted competence prefer masses 

 somewhat harder than this ; so, for instance, Heidenhain 

 (58), Apathy (55), Rabl (56), Mayer (58 to 60 in 

 summer; in winter about 56, but never less than 50). 

 Mayer points out that at Naples the temperature during 

 five months of the summer and autumn is over 22 C. in 

 the laboratory, sometimes over 30. Temperatures such as 



