14 LABORATORY EXERCISES 



into the water, and mark this point on the stick. Then wipe 

 the stick dry and put it into a test tube of kerosene. Does it 

 sink farther than in water, or not so far? Why? 



From Exercise 4, b, tell the density of water, under ordinary 

 conditions, in grams per cubic centimeter. Using the method 

 of Exercise 4, find the weight of 25 cu. cm. of kerosene. Calcu- 

 late how many grams 1 cu. cm. weighs (the density) . Compare 

 your result with that in the Appendix. 



c. Density of Shot. Take shot enough to fill about ^ of 

 your graduated cylinder, and get the weight of the shot. Have 

 the cylinder about half full of water, and get the volume 

 accurately. Be sure to read to the bottom of the curved sur- 

 face (meniscus). Then put the shot into the cylinder, and 

 read the new height of the water. Be sure that no air bubbles 

 are caught between the grains of shot. What is the volume 

 of the shot? What was its weight? Calculate the weight of 

 1 cu. cm. Of what is shot made? What is its density? 



Record all the results of this exercise systematically, as in 

 Exercises 2 and 4. 



EXERCISE 10 

 WEIGHT OF A STONE IN AIR AND IN WATER 



Apparatus and Materials. Balances (or scales), stone, thread, 

 beaker (or glass), water. 



a. In order to carry out this exercise we first weigh a stone 

 in air, as usual; we then suspend it from a balance and get the 

 weight it has when in water. The method of suspending the 

 stone depends on the kind of a balance we use. Fig. 6 shows 

 how to do it with a chemical balance; Fig. 7 is for a Trip scale; 

 Fig. 28, in 34 of the text, shows a third way. A spring bal- 

 ance (Fig. 11 of text) may also be used. 



Get the weight, in grams and tenths, of the stone and a 



