1JO 



THE MICROSCOPE. 



.-ilwavs. 



the diatoms in the stock bottle, and which, if not removed, would 

 prevent them from being evenly distributed over the covers. I say 

 rovers, for diatom.s should always be mounted upon these, and not 

 upon the slides. Now place upon the table as many covers as you 

 <lesire to mount, separated some little distance from each other, and 

 with the glass tube drop a portion of the contents of the small vial 

 of diatoms in water upon each. 'I'he vial should be gently shaken 

 between each dip, to distribute the diatoms evenly, and the amount 

 <^f fluid placed on each cover should be sufficient to extend to the 

 edge, and assume a convex form over it. The diatoms will distri- 

 hute themselves evenly over the whole surface, care being taken not 

 to disturb them by any jarring of the table. The dip is to be 

 made from the vial by thrusting the tube down nearly to the bottom 

 ,-ind closing the lop with the forefinger: the contents are deposited 

 »ipon each cover, by gently raising the finger and allowing the air to 

 t nter. A little practice is necessary to perform this successfully 

 Our rovers now being all ready, with watery burden cover- 

 ing the tiny diatoms, we light our spirit lamp 

 and carefully apply its flame beneath the 

 table, mf)ving it back and forth and occasion- 

 ally withdrawing it altogether, our object 

 ibcing to slowly evaporate the water, without 

 Icausing it to boil or in any way disturb the 

 cliatotns. As soon as the evaporation is com- 

 plete, the lamp may be left untouched and 

 the table heated to the highest degree pos- 

 sible, in order to insure a thorough drying of 

 the diatoms, which are now ready for the 

 final mounting. 



Place a slide upon the mounting plate and a minute drop of 

 pure balsam in its centre, and grasping one of the hot covers with 

 the forceps, turn it over upon the balsam, which will quickly spread 

 out to its edges, and the mounting is complete: done as quickly as 

 I can tell of it. If desired, the slide may be heated over the lamp 

 until all the turpentine is driven off, when, upon cooling, the cover 

 will be found firmly fixed; but the preferable way is to set it aside 

 for hardening in the usual manner. 'Phe smallest possible (juantity 

 of balsam should be used, and no ringing or other finish is necessary. 

 And now, having given hints as to various modes of making 



ni.ASS VIAl.S. 



