DENSITY 13 



pasted on the outside of the glass. Now set the glass aside in a 

 warm place, and watch it from day to day. What happens? 

 Remembering that there is a narrow space between the crust of 

 salt and the side of the glass, tell why the salt crawls up the 

 glass. What is the shape of the salt crystals in the bottom of 

 the glass? 



EXERCISE 9 

 DENSITY 



Apparatus and Materials. Block of wood, metric rule, balances, 

 graduated cylinder, kerosene, shot. 



a. Density of Wood. Measure carefully, to a millimeter, 

 the dimensions of a block of wood. A toy block will do. The 

 block must have rectangular or square faces. If, in measuring 

 any one of the dimensions of the block, say, the length, you 

 find that the distances along the four edges of the block are 

 not equal, take the mean length. That is, add the 4 lengths 

 together, and divide the sum by 4. In the same way get 

 the other two dimensions of the block, and then calculate 

 the volume of the block, in cubic centimeters. Now weigh the 

 block carefully, in grams and tenths; then divide the weight, 

 in grams, by the volume, in cubic centimeters. 



How many grams are there for each cubic centimeter? This 

 is the density, in grams per cu. cm. Of what kind of wood does 

 the block consist? Compare the density you have found with 

 that given in the Appendix of the text. 



6. Density of Liquids. Pour a little kerosene into a test 

 tube, and add some water to the tube. Do the liquids become 

 mixed? Which has the smaller density? 



Whittle a stick of wood (pine or white wood) to about the 

 thickness of a pencil and the length of a test tube. Put it into 

 a test tube that is nearly full of water. Note how far it sinks 



