46 



In the above method we found the percentage of 

 voids by weighing a certain volume of material. 

 Note the following parallel methods and results: 



Take a wash boiler or a water tight container of 

 approximately that size a water barrel would do if 

 there were nothing better. 



18 in. or so from the bottom drill a hole and put in 

 a spout, sufficiently long to carry the water into a 

 graduated glass standing beside the container. 



FIG. 23. BOX FOR MEASURING MATERIALS. 



A wooden box 10 in. by 10 in. by 20 in. containing 

 2,000 cu. in. (a little over i cu. ft.) can be made. Se- 

 cure a I gallon measure and a small graduate glass 

 (cu. inches) to measure less than a gallon. 



To determine the voids in crushed stone or any 

 aggregate or sand, proceed as follows : By filling up 

 the barrel until water runs out of the spout, and then 

 letting it run out until the surface is level with the 

 opening, we have a constant volume of water. Now 

 fill the box with the crushed stone. Pour the stone 

 slowly into the barrel, and measure the overflow in the 

 gallon measure. Use care to stop up the hole when 

 you are emptying measures, if a small measure is used. 

 There are 231 cu. in. in a gallon and you can determine 

 the number of cubic inches of water displaced by mul- 

 tiplying the gallons by 231, and adding the remainder 

 as measured in the graduate glass. It is self-evident 

 that this volume of water displaced is equal to the 

 exact volume of solid material in the 2,000 cu. in. of 



