126 EXPEEIMENT STATION RECORD. 



dered to it, the interior of the two chambers being thus connected. Tlie pair of 

 corrugated chambers are filled with petroleum as convenient during the course of 

 construction, and care is taken to exclude all air from the bulb, tube, and chamljers. 

 As the temperature in the bulb is made to rise it expands, and as both it and the 

 small tube have fairly rigid walls, the total expansion of the liquid is made to press 

 outwardly the walls of the chambers with corrugated walls, which expand and con- 

 tract after the manner of a bellows. An- upright post is fixed to the upper wall of 

 the pair of chambers, and it may be lengthened or shortened in making the necessary 

 adjustments. This post connects with a short arm 4 cm. in length, running to an 

 axis held in bearings between two upright standards. A second arm 17 cm. long, 

 carrying a pen, is attached to this axis and extends to an upright recording cylinder 

 revolved by clockwork. The cylinder carries double-ruled paper and occupies a 

 week in a single revolution. The instrument is now adjusted so that the pen bears 

 against the point on the paper indicative of the same temperature as that of the bulb 

 as determined by a mercurial thermometer, and it is ready for use. At the end of a 

 week the paper, bearing a continuous tracing of the temperature for that time, is 

 removed and another put in its place." 



Capillary studies and. filtration of clay from soil solutions, L. J. Briggs and 

 M. H. Lapham ( U. S. Dept. Agr., Bureau of Soils Bui. 19, pp. 40, figs. .5).— This includes 

 studies of the influence of dissolved salts on the capillary rise of soil waters, the cap- 

 illary movement of water in dry and moist soils, and filtration of suspended clay 

 from soil solutions. 



Influence of dissolved salts on the capillarij rise of soil vaters (pp. 5-18, figs. 3). — This 

 is a technical paper which discusses the factors modifying capillary action, describes 

 the methods and apparatus used in studying the effect of certain salts found in 

 alkali (sodium chlorid, sulphate, and carbonate) on this action, and explains the 

 significance of the results obtained. The following conclusions are drawn : " (1 ) Dis- 

 solved salts in general do not increase the capillary rise of soil waters. (2) Neutral 

 salts in dilute solution have practically no influence on the extent of capillary action. 

 (3) Concentrated or saturated soluti(ms of all salts materially diminish capillary 

 activity. (4) This effect appears to be due — («) To the increased density of the 

 solution, which more than offsets the increased surface tension, and — {h) To the 

 resistance of a film to a tangential shearing stress, which retards capillary action and 

 offers in addition a permanent resistance to the movement of the solution through 

 thin films, thus increasing the angle of contact, or — (c) To an increase in the tension 

 of the liquid-solid surface, as the concentration is increased. (5) Sodium carbonate 

 differs from neutral salts, the capillary rise being considerably greater than for 

 neutral solutions of equal concentration. (6) This may be due in part to the saponi- 

 fication of traces of grease on the surface of the soil grains througli the hydrolysis of 

 the sodium carbonate, thus furnishing clean surfaces for capillary action. (7) The 

 same effect should consequently be observed with all salts which undergo an alkaline 

 hydrolysis, viz, potassium and sodium carbonates, borates, phosphates, etc. (8) 

 This action is characterized in the soil tubes by indistinctness of the upper boundary 

 of the capillary column." 



The capillary movement of water in dry and moist soils (pp. 19-30, fig. 1). — This is s 

 technical account of the methods used and the results obtained in investigations on 

 this subject. From the latter the following conclusions are drawn: " (1) The extent 

 of capillary action in a soil under field conditions is not represented by the capillary 

 rise of water in the air-dried soil. (2) The extent of capillary action may, how- 

 ever, be found by determining the limiting height through which capillary move- 

 ment will take place in a moist soil. (3) If a general relation can be established 

 between the capillary rise of water in dry and in moist soils, then the capillary rise 

 in air-dried soils may be used as a basis for investigating the behavior of the soils 

 under field conditions, and possesses the advantage of greater simplicity. If no 



