Show Apparatus Separates 1 Parasites From Soil Ingenious Flotation Device of Dr Di Cobb Is Valuable Prepared b by th the United States Department of Agriculture In studying the which exist In the the soil and which In many cases cause diseases of plants such as root- root knot and certain rots there h has s been much difficulty in separating the organisms organisms organisms or or- from the soil soU Most of these threadlike parasites are extremely small and anU cannot be picked out by by ordinary methods neither can they b be w washed shed out r readily y However However Dr N. N A. A Cobb of the United Stat States s Department De Do- of Agriculture has devised an ingenious flotation app apparatus ratus which affords valuable aid in removing removIng removing ing nomad nomas nomas from a sample of soil The apparatus consists essentially of a hollow cylinder several Inches In diameter and three or tour four feet high tapering for about a afoot foot to a small opening at nt the bottom and provided with a spout near the top This cylinder cylinder cyl cyl- cyl- cyl inder is fastened to a circular rotating ing table or frame which is turned at a moderate speed by a n motor while nema free e water is run in from the thebo bo bottom tom by turning a graduated tap The soil sample Is mixed with a small quantity of water and then poured quickly Into the rotating cylinder when It is about a quarter full of ot water The rotation destroys any disturbing and up-and down and do currents which might Interfere interfere interfere in In- with the separation as in some ore separating machines sink very slowly and the therIse therise therise rise of the water Is so regulated by bythe bythe bythe the tap that It will a n little more than counteract their fall As a result the soil particles which are heavier sink to the bottom and the are lifted to the top the rising column of muddy water reaches the upper openIng openIng opening open- open Ing It Is spouted with the contained Into a vessel set on the rotating table to catch the overflow When all the are collected In this vessel vessel vessel ves ves- sel they are allowed to settle to the bottom The water is drawn off orr and anda a slimy mass containing the in much greater grenter concentration Is found In the bottom They may then be removed removed removed re re- re- re moved and examined under the micro micro- scope By this method also the num slum slumber number number ber of ot In a given quantity of soil may be estimated |