CHAPTER I 

 GENERAL LABORATORY INSTRUCTIONS 



Perform all experiments with care. Always read through 

 the directions before beginning work. Record results imme- 

 diately after they have been observed. Do not wait until a later 

 time and then trust to your memory. 



Be neat and careful in your work. 



Always return reagent bottles to their proper places imme- 

 diately after using. Keep your desk and apparatus clean and in 

 good order. After being used, apparatus should be thoroughly 

 cleaned before it is put away. Wash it with tap water, using a 

 brush, and finally rinse with distilled water. Greasy materials 

 can be removed with warm water and soap. If these means are 

 not effective, use cleaning fluid (potassium bichromate and con- 

 centrated sulphuric acid). Do not throw the cleaning fluid 

 away. Return it to the vessel from which it was taken as it can 

 be used again. Glassware cleaned with cleaning fluid should be 

 rinsed thoroughly with tap water and finally with distilled 

 water. 



Do not put a pipette or dropper into any reagent bottle. If 

 a reagent must be measured with a pipette, pour out a small 

 amount into a clean dry beaker, or test tube, and take up with 

 a pipette from this vessel. If more of a given laboratory reagent 

 has been taken from a bottle than is needed, do not return the 

 excess to the original bottle. Be careful not to pour out more of 

 the reagent than you require, but if excess has been taken it 

 should be thrown away. 



In using alcohol, ether, acetone, benzol, etc., make sure that 

 no fire is near. Ether vapor is especially dangerous, as it may 

 flow along the desk top for some distance and ignite at a neigh- 

 boring Bunsen burner. Small desk fires often may be put out by 



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