THE SOIL PARTICLE 



87 



as based on the original sample. This is 

 every method of mechanical analysis in 

 utilized aims to do, although often the 

 technique are excessively complicated. 



65. Mechanical analysis by water in 

 motion. Schone's elutriator. — Any ap- 

 pliance that is designed to separate 

 particles of different sizes by water in 

 motion may be designated as an elutria- 

 tor. One of these, commonly used in 

 Europe, is called Schone's elutriator.^ 

 This utilizes hydraulic force. In it the 

 upward current of water ascends a coni- 

 cal glass tube (see Fig. 11) from a 

 narrow curved inlet tube below. The 

 soil sample present in the inlet tube is 

 kept agitated by the current. It is evi- 

 dent that by regulating the rate of flow 

 of the water, different sizes of particles 

 will be_ carried away over the top of 

 this conical glass tube. Thus by a gentle 

 flow only fine grades will be separated, 

 while by increasing the current larger 

 and still larger particles will be carried 

 upward against the force of gravity. 



There are three objections to this 

 method: first, the entrance tube may 

 become clogged, and, unless a very small 



precisely what 

 which water is 

 apparatus and 



f/ 



Fig. 11. — Sehone's 

 elutriator for me- 

 chanical soil 

 analysis with 

 water in motion. 



^ Schone, E. Ueber Sehlammanalyse. Bui. Soe. imperiale 

 des Naturalistes de Moscow, 40, Part 1, p. 324. 1867. Uber 

 Sehlammanalyse und einen neuenr Schlammapparat. Berlin, 

 1867- Also see Wiley, H. W. Agricultural Analysis, YoL I, 

 pp. 231-241. Easton, Pa. 1906. 



