. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 40 BULLETIN 314, ⢠TJ. S. DEPARTM-ENT OP AGRICULTURE. X. If* The cylinders are constructed for this purpose by drilling a hole in fche center of the bottom of each. This hole should be slightly larger than the outside diameter of the brass tubing, one end of which is cemented into it by means of a litharge and glycerin mixture. The upper end of the tube should be flush with the inside of the bottom of the graduated cylinder and in the large cylinder a piece of 200- mesh wire gauze should be soldered over the end of th
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 40 BULLETIN 314, ⢠TJ. S. DEPARTM-ENT OP AGRICULTURE. X. If* The cylinders are constructed for this purpose by drilling a hole in fche center of the bottom of each. This hole should be slightly larger than the outside diameter of the brass tubing, one end of which is cemented into it by means of a litharge and glycerin mixture. The upper end of the tube should be flush with the inside of the bottom of the graduated cylinder and in the large cylinder a piece of 200- mesh wire gauze should be soldered over the end of the tube to prevent fine material passing through. The apparatus is set up as shown in figure 20, with the pinchcock on the rubber tubing closed. The small cylinder is filled with kero- sene, after which the pinchcock is slowly opened in order to â a permit the kerosene to â J) force any air from the tubing and to come flush with the bottom of the large cylinder. The pinchcock is then closed. The aggregate is thor- oughly mixed and quar- tered, if necessary, until a representative sample of material of at least 300 cubic centimeters volume is obtained. This sample of aggre- gate is poured into the large cylinder, a scoop- Fig. 20.âApparatus for determining voids in the mineral aggregate. , . . -, 1 ⢠i . f ul at a time, with a light tamping of the cylinder against the rubber pad in order to compact the material. Best results are usually obtained by making a cylinder of manila paper inside the glass cylinder, and introducing the aggre- gate inside the paper. The paper can then be slowly withdrawn while the glass cylinder is being lightly tamped. Segregation of the several sizes of material must be avoided, and any fine material remaining on the paper should be brushed off and added to the aggregate. When the aggregate in the large cylinder has reached its maximum state of compaction, the volume of kerosene in the small cylinder is read, the pinchcock is opened and the elev
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