100 CHAPTER VIII. 



benzol, which should be changed once or twice so as to make 

 sure of removing all the alcohol, and then adds to the pure 

 benzol some small pieces of paraffin, and lets them dissolve 

 in the cold. After several hours (up to eighteen) the whole 

 is brought in an open vessel on to the cold water-bath, the 

 bath is then warmed gradually so as to attain a temperature 

 of 60 C. in about two hours, and as fast as the benzol 

 evaporates melted paraffin is added to it. Lastly, the paraffin 

 is changed once before the definitive imbedding. He rarely 

 leaves objects over night in the water-bath. 



APATHY (Mikrotechnik, pp. 149-150) first clears with oil 

 of cedar, then brings the objects (by the process described 

 106) into a solution of paraffin in chloroform saturated at 

 the temperature of the laboratory. The objects remain in 

 the chloroform-paraffin solution for from one to three hours, 

 without warming, until all the cedar oil is soaked out of 

 them. The whole is then warmed on the water-bath or oven 

 to a few degrees above the melting-point of the paraffin 

 intended to be used for imbedding, and the object is brought 

 into a mixture of equal parts of paraffin and chloroform, 

 being suspended therein near the top on a bridge made of 

 hardened filter paper (or in a special apparatus to the same 

 end, not yet described). It remains in this mixture, at the 

 temperature of the oven, for one to three hours, and lastly 

 is brought (still on the paper bridge or in the apparatus) 

 into pure paraffin, where it remains for half an hour to two 

 hours. 



HEIDENHATN (Festschr. f. Koelliker, Leipzig, 1892, p. 114) 

 clears with bergamot oil, and passes into pure paraffin 

 through mixtures of the oil and paraffin. RABL also (Zeit. 

 f. wiss. Mik., xi, 1894, p. 164) employs bergamot oil. 



\v 

 130. Water-baths and Ovens. It is important that the paraJfin 



should not be exposed to a moist atmosphere whilst it is in the liquid state. 

 If a water-bath be used for keeping it at the required temperature, provision 

 should be made for protecting the paraffin from the steam of the heated 

 water. 



A very convenient apparatus for this purpose is that of Paul Mayer, or 

 " Naples water-bath," which will be found described at p. 146 of Journ. Roy. 

 Mic. Soc., 1883. It may be procured from the opticians, e. g. Mr. Baker. 

 See also Amer. Natural., 1886, p. 910 ; and Journ. Roy. Mic. Soc., 1887, 

 p. 167. 



