132 University of California Publications in Agricultural Sciences [Vol.3 



the tube, a plate placed over it and pressure applied in a machine of 

 a capacity of 200,000 lbs. to the square inch. About 25 c.c. of liquid 

 were thus obtained from eight pounds of soil. The result of this ex- 

 periment was unsatisfactory, owing to the small amount of liquid 

 obtained from a soil with an optimum moisture content. I determined, 

 therefore, to use a tube with a much smaller diameter (1 to 2 inches), 

 so that the pressure exerted by the machine could be concentrated 

 on as small a surface as possible and thus rendered more efficient. 

 When such a tube was made, other difficulties were encountered. A 

 few months later, these were surmounted and revised forms of appa- 

 ratus were thus prepared from time to time as other duties permitted. 

 No form of these was satisfactory even though I had demonstrated 

 that small amounts of the soil solution could be obtained with some 

 of them. During the last few months, however, I have had the privi- 

 lege of the counsel of Mr. C. T. Wiskocil of the Department of Civil 

 Engineering of this university, who has designed a new form of 

 pressure tube for my purposes. Such a tube was made up and we 

 have tried it out. recently, on several occasions with gratifying results. 

 In the case of a very fine sandy soil containing an optimum moisture 

 percentage (about 15% by weight), nearly two-thirds of the moisture 

 was expressed from samples of 300 to 400 grams of moist soil. In 

 the case of a clay loam soil, we were not so successful, but from two 

 or three samples of about 300 grams each of such a soil containing 

 about 20% of moisture (by weight), we obtained enough of the soil 

 solution to make conductivity measurements and, if needed, quanti- 

 tative analyses. Certain difficulties were encountered in pressing the 

 clay loam soil, which did not obtain in the case of the fine sand, but 

 these were also surmounted by another suggestion originating with 

 Mr. Wiskocil. Even now we find that our apparatus needs to be 

 changed, or a new one must be made to stand pressure in excess of 

 50,000 lbs. to the square inch, so that greater efficiency in pressing 

 clay loams and clays- may be attained. The detailed description of 

 our apparatus, and of the results of conductivity measurements and 

 analyses of the solutions obtained are reserved for description in 

 another paper in which due credit will be given Mr. Wiskocil and 

 Dr. D. D. Waynick for invaluable assistance rendered in connection 

 with these matters. 



My principal object now is to direct the attention of my colleagues 

 in soil investigations to the fact that, after nearly four years of desul- 

 tory effort, I have succeeded in demonstrating that direct pressure 



