4 ELEMENTS OF LABORATORY WORK 



act at the same point on the beam (namely, at the knife-edge 

 itself). 



4. Observe the use of the pointer and scale. 



Hi- 



. 1. 



Additional Exercises and Questions. 



1. Construct a set of fractions of a gram from platinum foil and 

 aluminium foil, ttse a pair of scissors for cutting away, and impress 

 the value on each when correct. 



2. How may equal quantities of matter be determined on a balance 

 which has unequal arms ? What arguments may be used in support of 

 your method ? 



3. Describe exactly what is meant by saying that a given body 

 weighs 3'3 grams, and give the operations by which this knowledge of 

 the body is obtained. 



4. How many milligrams are contained in 103*725 grams ? What 

 fraction, vulgar and decimal, of a gram is the quantity 7 centigrams 

 together with 11 milligrams? 



5. Why is it best to stop the balance from swinging when the pointer 

 is at the centre of the scale, and why should the weights never be 

 altered when the balance is swinging, or the pans breathed upon when 

 an observation is being made ? 



6. Which is the best method of judging when there is exact counter- 

 poise O) by seeing whether the pointer comes to rest at the centre 



