4 THE MICROSCOPE. Jan. 



. Microtome Knives and Their Care. 



By BAUSCH & LOMB, 

 ROCHESTER, N. Y. 



The requisites for good work in microtomy are, aside 

 from the manipulative skill and the preparation of the 

 specimen, a perfect working microtome and a good knife. 

 The latter particularly, for, if the cutting edge is not in 

 the best of condition, no good sections can be secured ; 

 we have had so many complaints from this source and 

 for the reason that so few know the real modus operandi 

 to obtain a keen cutting edge, that we present these 

 instructions how to proceed to sharpen a knife and keep 

 it in good condition. 



We recommend to commence with, the yellow B^gian 

 hone for the reason that it is the best obtainable ; in 

 using it, cover with palm oil soap and moisten freely 

 with clean water so that a lather will be formed which 

 must be kept during the entire time the knife is being 

 sharpened. This soap has the advantage over the ordi- 

 nary oils in use for honing in that the pores of the stone 

 remain open, whereby quicker sharpening as well as a 

 better edge and easier cleaning of the knife are the 

 result. If a microtome knife is very dull or perhaps has 

 small nicks in it, it is very essential to first sharpen it 

 on a yellow stone and then draw it several times over a 

 blue stone in order to obtain an exceedingly keen edge ; 

 with the blue stone is used a softer stone called " rubber" 

 which is necessary, for, after the blue stone has been 

 moistened with water, it is used to grind down the scum. 



To begin with, the knife is sharpened on the concave 

 side until a fine thread is formed on the cutting edge, 

 which can easily be seen by drawing the knife across the 

 finger nail ; when this thread becomes visible along the 

 entire cutting edge, the knife is passed without any pres- 

 sure over the already prepared stone but in such a man- 



