14 LABORATORY METHODS AND EQUIPMENT 



E. Rules for the use of tlie microscope : 



1. Never allow the objective to touch the cover glass or the 

 liquid in which the object is mounted. 



2. Do not handle the front lens of the objective or unscrew 

 the sections in which the lenses are mounted. 



3. Clean the front lens of the objective only when neces- 

 sary, and then with small pieces of lens paper, which should 

 be thrown away after use, or with an old clean, soft hand- 

 kerchief. Breathe on the lens before cleaning it, or, if that 

 is not sufficient, moisten the lens paper with a drop of 

 alcohol or xylol, taking care to wipe it perfectly dry as 

 quickly as possible. 



4. Do not let the objective remain long near volatile corro- 

 sive liquids such as hydrochloric or nitric acid or strong 

 solutions of iodine. 



5. Do not allow liquids to run from the slide over the stage 

 or other parts of the microscope. 



6. Keep the microscope covered with a bell jar or paper 

 cone when not in use, and keep the objectives and eye- 

 pieces away from dust. 



