CHAPTER VIII. 



IMBEDDING METHODS PARAFFIN AND OTHER FUSION MASSKS. 



138. Saturation with a Solvent.- -The first stage of the 

 paraffin method consists in the saturation of the object with 

 some substance which is a solvent of paraffin. The process 

 is sometimes called " clearing," since many of the substances 

 used for infiltration are also "clearing" agents. 



The process of saturation should be carefully performed 

 with well-dehydrated objects in the manner described in 



H 9 - 



Saturation liquids being liquids that are, on the one hand,, 



miscible with alcohol, and on the other hand good solvents 

 of paraffin, are not quite as numerous as could be wished. 



According to GRAEFE (Clicm. Centralb., 1906, p. 874), at 

 20 C. petroleum ether (1 c.c.) dissolves 200 mg. of paraffin ; 

 chloroform 246; benzol 285; carbon tetrachloride 317. 

 And according to APATHY, at 20 0. benzol dissolves 8 parts 

 per cent., chloroform 10, toluol 10, xylol 12, oil of turpen- 

 tine 8, cedar oil 4 to 6, bergamot oil 0'5 to 3, creosote and 

 clove oil hardly any. Acetone, according to MAYER, dissolves 

 hardly any. 



Turpentine I do not recommend, because in my experience 

 it is of all others the clearing agent that is the most hurtful 

 to delicate structures. 



Clove oil mixes very imperfectly with paraffin, and quickly 

 renders tissues brittle. 



Oil of bergamot mixes still more imperfectly with 

 paraffin. 



Benzol has been recommended by BRASS (Zaf. u'ms. Mik., 

 ii, 1885, p. 301), and is now much used. 



Toluol (or toluen) has been recommended by Ilnu, (Zool. 

 Anz., 1885, p. 223). 



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