138 THE MICROSCOPE. 



tie. Add an ounce of strong ammonia water, or half that quan- 

 tity of liquor potassse, shake up, and you will have a liquid 

 soap that will remove from the hands or clothing any of the 

 gums, cements, etc., used in mounting. Even marine glue yields 

 to it like magic. 



Sharpening the little knives used in minute dissections is one 

 of the most difficult things to even old workers, and yet one of 

 the simplest imaginable after you get the hang of it. I use for 

 this purpose three hones — a quick-cutting, somewhat coarse, 

 barber's hone (those backed with slate are best), a fine hone of 

 the same sort, and lastly, the finest Ouachita (Hot Spring) hone. 

 Soap and water, or lather, is used to keep the hone wet. If the 

 knife is quite dull, commence with the coarse hone. Lay the 

 blade perfectly flat on the stone and move it, edge foremost, 

 straight over the stone, being careful to carry the hand with it 

 in such manner that the blade shall remain flatly in contact 

 with the hone the entire distance. This is the first secret of 

 success, and you will find it somewhat difficult to accomplish at 

 first; but with a little care and attention the movement soon be- 

 comes automatic. Do not bear or press on the blade. This is 

 the second essential point. Let the blade slip lightly over the 

 stone, in exact contact, but exert no undue pressure. If you 

 do, the blade bends at some point and wears away there, instead 

 of somoothly all along the surface. Having removed sufficient 

 of the metal and secured a roughly-sharp edge, take the second 

 or smooth hone, and proceed in the same manner, keeping 

 plenty of lather on the stone. One way of judging whether your 

 blade is laying quite flatly on the surface is to note whether it 

 moves the bubbles of lather to one side or the other, or whether 

 it slips under them, leaving them in place. The latter is the 

 way it should do. A few passes on- this stone will be sufficient. 

 The finishing on the Arkansas hone is performed in the same 

 manner, only greater care should be exerted to prevent any pres- 

 sure. When the knife comes from this hone it should be bright 

 and polished almost as smoothly as though it had been against 

 a polishing buffer. It is now ready for use. A strap for such 

 knives, indeed, for any knife, is an abomination. It simply 

 rounds and dulls an otherwise perfect, wedge-like edge. If a 

 point has been broken off restore it on the coarse hone first, be- 

 fore you commence to sharpen. To this end, pass the blade, if 



