90 SOILS: PROPERTIES AND MANAGEMENT 



outlet, carrying with it a sediment the size of which 

 depends on the rate .of water flow and the strength of 

 the centrifugal force. The bottle is so designed that 

 particles in all parts of the separating chamber are sub- 

 jected to the same force, no matter what their distance 



Fig. 13. — Separatory bottle of Yoder's centrifugal elutriator. (B), Bottle ; 

 (e), intake ; (a), tube for conducting liquid to bottom of separatory 

 bottle; (o), outlet; (C), centrifuge ; (u>), counterpoise. 



from the center of the centrifuge may be. The apparatus 

 can be used only for separating particles less than .03 

 millimeter in diameter. It is open to the same objections 

 that apply to Hilgard's machine, besides being very much 

 more complicated and delicately adjusted. It is too 

 costly an apparatus for ordinary work. 



68. Mechanical analysis by water at rest. Osborne's 

 beaker method. — One of the earliest and most nearly 

 accurate methods to be perfected was the separation of 

 the various grades of soil by simple subsidence in a column 

 of still water. This is commonly spoken of as the Os- 

 borne beaker method. 1 The determination is very 

 simple. The soil sample is first fully deflocculated and 

 thrown into suspension, each particle functioning sepa- 

 rately. Beakers are commonly used as containers, but 



1 Osborne, T. B. Methods of Mechanical Soil Analysis. Ann. 

 Rept. Connecticut Agr. Exp. Sta., 1886, pp. 141-158; 1887, pp. 

 144-162; 1888, pp. 154-157. 



