The Microscope. 183 



with vegetable wax are obtained as follows (Bull. Soc. Belg. de 

 Micr.): The object is placed in 94 per cent, alcohol and kept at 48° 

 C over a water-bath. When the required elevation of temperature 

 is obtained, small pieces of the wax are added to the spirits until a 

 mixture having the consistency of soft soap is obtained. This mass 

 is then placed in a bulb having a straight cooler about three feet 

 long, so that the alcohol, as it condenses, will fall back into the 

 bulb. When saturation of the object is accomplished, it, with the 

 mass, is removed to another vessel, the alcohol evaporated off, and 

 the specimen cast in a card-board or metal box. The subsequent 

 treatment of the sections is somewhat troublesome, and possesses no 

 advantages over the other methods. 



One of the latest substances for embedding is suggested by 

 Krysinski [Virchoi&s Archiv). This is photoxylin, a kind of 

 pyroxylin used by Russian photographers, and which Krysinski 

 considers superior to celloidine on account of its keeping without 

 deterioration, and remaining clear in solution or mass. Mr. George 

 M. Beringer [American Journal of Pharmacy, May, 1888), who 

 has experimented in the production of photoxylin, finds that the 

 following formula gives the best results: 



"Nitrous acid, 43° R 3^ lb. av. 



Sulphuric acid 4^ lb. av. 



Potassium nitrate, granular 8 oz. av. 



Wood pulp 4 oz. av. 



" The nitrous and sulphuric acids are mixed in an earthenware 

 crock and allowed to stand until the temperature has fallen to 90*^ 

 I"., when the potassium nitrate is added and thoroughly incorporated 

 with the acid mixture. The wood pulp is then immediately 

 immersed in the mixture and allowed to remain for twelve hours. 

 It is then removed from the acid and thoroughly washed." 



The material thus obtained is quite soluble in equal parts of 

 ether and absolute alcohol. For general work, K. recommends two 

 solutions : a thin solution (^ to 1 per cent), and a 5 per cent. The 

 specimen is placed from strong alcohol into the thin solution, to 

 remain from twelve to twenty-four hours, when it is transferred to 

 the thicker solution. To fix the specimen before cutting, it is only 

 necessary to place it on a cork, A film soon spreads over the mass, 

 which is then submerged in 70 per cent, alcohol, and after two or 

 three hours, is ready for sectioning. This material is not at present 

 obtainable in this country, but as it bids fair to rival collodion 

 in surgical practice, it will undoubtedly soon create a demand and 

 production. 



