NOTES AND MEMORAMDA. 101 



White Cement for Final Coating in Microscopic Mounting, 

 liy B. Wills Richardson, F.R. C.S.I. — A Avhite cement for 

 final coating in microscopic mounting, and one which admits 

 of being used cold, has been employed for some years abroad. 

 It is known as " Ziegler's White Cement." 



Frey has found that it may be employed alone with per- 

 fect security, e. e., without being preceded by another cement. 

 He states also that it has been " recently improved by Herr 

 Meyer, the proprietor of the Hirsch Apothecary, in Frank- 

 foit."i 



A great objection to this cement is its slow-drying pro- 

 perty. It '•' generally dries very slowly," says Frey, who 

 mentions likewise that " portions of the cement which have 

 run over the surface of the cover should be left untouched 

 for months." It can scarcely, therefore, be considered a 

 manageable preparation. 



The composition of Ziegler's cement being a secret, it 

 has been imitated by Stieda, who, Frey observed, we have to 

 thank " for a communication giving the directions for com- 

 posing a similar cement. Oxide of zinc is to be rubbed up 

 with a corresponding quantity of oil of turpentine, and while 

 rubbing, for each drachm of the oxide of zinc an ounce of 

 a solution of the consistence of syrup of gum damar in oil 

 of turpentine is to be added. If another colour than white 

 be desired, cinnabar may be used in the place of the oxide 

 of zinc, using two drachms to the ounce. "^ 



The white cement I have been for some time using with 

 glycerine mountings resembles Stieda's cement in containing 

 the oxide of zinc and gum damar. The other ingredients, 

 however, are different. 



It is a pure white, dries in from two to forty-eight hours, 

 the rapidity of drying depending upon the amount of dis- 

 solved damar it contains ; does not crack, is used without 

 heat, will not run, and dries with an even edge. 



It is made as follows : — Two ounces of pure well-ground 

 oxide of zinc are to be rubbed up with a sufficient quantity 

 of drying oil to the consistence of thick paint, to which is 

 then to be added an equal part of gum damar dissolved to 

 the thickness of syrup by means of benzoline. When 

 thoroughly incorporated, strain through a tolerably close- 

 meshed lace, and keep in a wide-mouthed well-corked bottle. 

 When necessary, thin with benzoline ; and should the cement 

 not dry sufficiently glossy add more dissolved gum damar. 



' ' Tlie Microscope and Microscopical Technology.' By Dr. Heinricli Frey, 

 translated by George R. Cutler, M.D., New York, ] 872. 

 2 Ibid. 



