The Microscope. 27 



very troublesome to the beginner as well as to the more ad- 

 vanced. 



In the first place the balsam should be not too thick nor yet 

 too thin, and, except for objects that will not stand any heat, 

 should be the pure natural balsam ; the hard dry balsam dis- 

 solved in chloroform, benzol, etc., should, in my judgment, be 

 only used when absolutely necessary, by reason that the object 

 is too frail to stand the heat of baking. 



The nicest and cleanest way to handle the balsam is in the 

 collapsible tin tubes Dealers in microscopical supplies furnish 

 the filtered balsam in these tubes at twenty-five cents an ounce. 

 I could never see why they should charge such an enormous 

 profit for filling these tubes with balsam, as the balsam can be 

 bought at retail for seventy-five cents a pound, and the tubes are 

 worth less than two cents each. The amount to be used can by 

 these tubes be graduated to a nicety, and if filtered no dirt can 

 ever get in the balsam. It is needless to say that the slide and 

 cover glass should be clean. I find the best way is to clean them 

 just as you use them, using dilute alcohol and an old handker- 

 chief. After cleaning, warm the slide to get rid of moisture, 

 place on your turn table, and apply the balsam (or if the object 

 is frail, float it on the slide before applying the balsam); the ob- 

 ject after being placed on the slide can be covered with a little 

 more balsam, it being best to use more balsam than will be re- 

 quired in the finished mount. The clean cover glass should now 

 be held by the forceps near the flame of a Bunsun gas flame or 

 that of an alcohol lamp, to free it from moisture, as well as to pre- 

 vent air bubbles; then it may be gently lowered from one side 

 over the object ; a clip may be now applied, unless the object is 

 too frail to stand the pressure of it. I find the best clip can be 

 made from the ordinary steel hair pins by bending one part of 

 it so it will lie flat on. the bottom of the slide without turning 

 over, and bending the other part at right angles so the point will 

 press against the cover glass. Stray air bubbles and small pieces 

 of dirt can be removed with a fine wire, after the cover has been 

 applied. Disarranged objects can also be replaced by the same 

 means. Baking the slide is next in order ; the heat should not 

 be very great. I find the best plan is to place the slides on a 

 board, and put in the oven of an ordinary cook stove or range, 

 after the fire has been fixed for the night ; by morning, the slides 



