TiiK Bulletin. 7 



dale tlic sample is received, by wIkhu subiuilted, and any additi(nial 

 iul'onnatioii that may accompany it. Ju brief, the details of making a 

 purity tost are as follows: the entire sample is put into a mixing and 

 separntiiiii,' machine, which thoroughly mixes the entire lot and divides 

 it into :ib(»ur the approximate amount of the sample to be used for the 

 test. An exact amount of this is then weighed out on nn analytical bal- 

 ance. Different amounts are used for the different sized seeds, as less 

 is required for a fair test of the snudler seeds than of the larger ones. 

 The approximate amount used for the various seeds is given in Table II 

 showing the occurrences of foreign seeds, page 12. The definite amount 

 of seed which has been weighed out is placed upon a specially constructed 

 board with sloping arm rests, for convenience in working, and covered 

 with Avhite paper so that the seeds may be seen distinctly, and by means 

 of a pair of small steel forceps the pure seed is separated from the 

 foreig-n seed and inert matter. Magnifying glasses are also used in 

 doing this Avork. The three separations are now weighed and the per 

 cent of each determined. 



In reporting a test, these per cents are given and also the approxi- 

 mate number and common name of all weed and other seeds tliat occur 

 per pound of sample. In this way a farmer is able to know just how 

 many and Avhat kind of foreign seeds he sows upon his land by planting 

 this seed, and how much waste matter he is buying. The occurrence 

 of dodder in red clover and alfalfa is so serious that seed should be 

 rejected that contains even a trace of this pest. For this reason, if 

 dodder seed is not found in the regular test of five grams for these seeds, 

 a larger amount of the sample (fifty grams) is examined, and if found, 

 its presence is reported. 



The work of making a purity test is really the work of a specialist, 

 but a great deal can profitably be done by the farmers in the way of 

 examining the seeds they huy and determining the impurities. By sepa- 

 rating a definite portion of the sample into the three parts, pure seed, 

 inert matter, and foreign seed, an estimate may he made of the impuri- 

 ties without Aveighing. Seeds of approximately the size of red clover, 

 about a tahlespoonful, should be used for an examination, and of the 

 larger seeds more should be used. It is often not as important to know 

 the amount of impurities as the kind, as a few seeds of certain noxious 

 weeds, for instance, dodder, are far Avorse than a greater number of 

 some less harmful weeds. 



An examination should not be attempted Avithout the aid of a magni- 

 fying glass. A very good one is shoAvn in Fig. 1, Avhich may be obtained 

 at any bookstore for tAventy-five or fifty cents. A reading glass may 

 also be used very successfully and a penknife or paper-knife, in the 

 absence of forceps, may be used in separating the seed; in fact, some 

 persons prefer these to forceps. The seed to be examined, after being 



