MASS ANT) ITS MEASUREMENT 



supports on which they rest are made of 

 mineral, instead of being constructed of steel. 



a very hard 



EXIT. 53. -Uncover the balance and identify the different 

 parts by reference to Fig. 22. Raise the beam, AB, of the 

 balance, off the supports by turning the handle C. Notice 

 whether the pointer F swings equally on both sides of the 

 middle of the scale G : if it does the balance is ready for use ; 

 but if not, let down the beam and turn the mall screw 



1 FIG. 23. A Chemical Balance. 



at B, then try again. Repeat this adjustment until the 

 swings to right and left are equal. 



EXPT. 54. Put some shot in a watch-glass, and place it 

 in the left-hand pan, E, of the balance. Examine your box 

 of weights, and, selecting a weight which you estimate to 

 l)e about the same as the shot, take hold of it with the forceps 

 and place it in the right-hand pan (the weights should always 

 be placed in this pan). Now slightly raise the beam to see 

 whether the estimated weight is nearly equal to the weight of 

 the shot. If the weight appears a little below what is wanted, 

 pick up, with the forceps, the next heaviest weight in the 



E 2 



