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CENTRAL SCIENTIFIC CO., CHICAGO, IT. S. A. 



No. 12268 



No. 12264 v^- tj No 12272 _ 



COMPACTING MACHINE, Continued. 



peller is placed at the bottom of the tube to be filled and soil then poured into the tube. 

 Twice during each revolution it drops with the soil tube, thus striking a definite number of 

 blows on the soil column as it rises. 



This compactor is built to compact soils to approximately the same condition in which they 

 are found in the fields and to give uniform compaction for comparative tests. It is simple 

 in principle and does its work quickly and easily. With two propellers (one for 2-inch tubes 

 and the other for 4-inch tubes), weight holder, and weights $30.00 



12258. COMPACTOE, Spring Board, necessary for compacting soils in glass tubes. Base of wood 8x24 

 inches; spring board firmly fastened to base at one end; massive slip-weight slides on nickel- 

 plated rod. A very substantial and well-finished piece 7.00 



12262. CONDUCTIVITY APPARATUS, for determining the thermal conductivity of soils. This design 

 has been modified from the original design in use at the University of Illinois Soils Labora- 

 tory. A galvanized iron soil tray, 16x4x5 inches, has at one end a water-tight boiling tank, 

 4x4x5 inches. Attached to this tank is a heating coil, as shown in the illustration, by which 

 the water in the tank can be kept at the boiling point indefinitely. By this method of heat- 

 ing, the errors present in the old apparatus due to direct heating from the flame are entirely 

 avoided. The boiling tank is provided with tubulatures for thermometer and for reflux con- 

 denser which may be used if desired. Complete as illustrated 6.00 



32264. CONDUCTIVITY APPARATUS, similar to No. 12262, but without heating coil and with an 

 electrical heating unit. This method of heating was suggested by the Department of Soil 

 Technology of the New York State College of Agriculture at Cornell University and has 

 proved very satisfactory. For 110-volt current, either alternating or direct. Power consumed, 



350 watts 11.00 



For CONDUCTIVITY BRIDGE, see No. 12400. 



12268. DIGESTION CUP, porcelain, for acid digestion of soils (Hilgard's Method). Capacity, 50 cc .35 

 DISHES, Moisture, see general heading Dishes. 



12272. DRAINAGE AND WATER TABLE APPARATUS, Graham & McCall's, designed to show the 

 behavior of capillary and free water in the soil, and the principles involved in the proper 

 construction of a barnyard to prevent loss of plant food; of copper, 3x6x12 inches high, with 

 a solid bottom to represent hard clay or stone. Through the vessel are two brass tubes, sawed 

 transversely, which communicate with the outside, representing tile drains at different depths. 

 A standpipe shows the height of free water inside the vessel. 



To operate, fill the vessel with soil and pour on water at regular intervals, giving it time to 

 soak into the soil. The water, instead of coming out at the tubes, will pass downward through 

 the soil until the solid bottom is reached, when a water-table of free water will be formed 

 at a height indicated by the free water in the glass standpipe. When the free water has risen 

 to the first opening it will pass outside the vessel, thus proving that a tile drain placed as 

 low as soil conditions will permit removes free water before one placed not so deep. 



