138 



THE MICROSCOPE. 



in which the former are to be mounted. Very many processes for 

 cleaning the shps and covers have been given to the world by vari- 

 ous writers, and probably they are all good. I give only my own, 

 which I have used for many years, with entire satisfaction, and 

 therefore can confidently recommend it. The slips (which should be 

 smooth edged), are placed in a basin with hot water and good soap, 

 and wiped dry with a soft towel, after being thoroughly 

 washed and rinsed. They are then placed in a drawer, 



and are ready for use at any future time, merely requiring to be 

 brushed off with the large camel's hair pencil when used. The thia 

 covers (which should always be circles, and not squares, as making 

 neater and more readily finished mounts), are dropped one by one 

 in a glass tumbler, containing sulphuric acid, 

 and allowed to remain there for some hours. 

 The acid is then poured off, and water carefully 

 added, which in its turn is decanted and re- 

 placed with fresh water, the whole contents of 

 the glass being freely agitated until every 

 trace of the acid is removed. One of the glass 

 pomatum jars is now to be partially filled with 

 alcohol, and the thin covers placed therein to 

 remain until wanted for use, when they can be 

 removed with the forceps, and a slight wiping 

 with an old, soft linen handkerchief will leave 

 them brilliantly clean. 



My own preference is for absolutely pure filtered balsam as af- 

 fording the most satisfactory results in all sorts of mounts, but that 

 from which the spirits of turpentine has been expelled by heat, and 

 replaced by chloroform or pure benzole, answers a most excellent 

 purpose, whilst the many damar mediums are also good. But 

 following the plan upon which this article was begun, of giving 

 only those processes, which I habitually practice, and know to be 

 satisfactory, I shall confine myself to pure balsam alone. 

 The great secret in its successful use is to have it of just the proper 

 consistency, neither hard enough to resist the thrusting of a fly's 

 wing into a drop of it when placed upon the slide, or so limpid as 

 to spread and run when so placed. If too thick, a little chloroform 

 carefully stirred into the bottle containing the balsam, will reduce it 

 to proper consistency; if too thin, a covering of cotton cloth should 



Mounting table with 

 lamp. 



