34:6 



Missouri Agricultural Report. 



only a small sample of seed can be used in the test. A large sample would 

 require too much time and labor. For this reason only small samples are 

 used in making official tests of seeds. 



The absence heretofore of a readily available, effective balance suited 

 to this work doubtless has been the chief bar to the popularizing of farm 

 and rural-school seed testing. Expensive chemical balances are used in 

 making official tests, and the cheaper balances on the market cost from 

 $10 to $35 — an expense beyond the reach of the mass of consumers who 

 should profit by practical seed tests. 



The Balance. — A simple, efficient balance can be made by any boy 

 or girl at all familiar with the use of a few common tools. The general 



Fig. 15. — A simple balance used in making- the purity test of seeds : a, Six-sided 

 pencil, full length, and a half-length pencil bound to tlie long pencil by rubber 

 bands ; c, shallow holes near the ends of the long pencil ; d, reference mark 

 common to both pencils at a convenient point on the line where they meet; e, 

 trays for holding the seed and the weights, tlie upper one showing the under 

 side ; f, bluntly pointed end of the wire adapted to fit loosely in one of the lioles 

 (c) ; g-, wire bent beneath the tray to hold it in position ; h, piece of gummed 

 paper holding the wire to the tray ; i, hole at proper distance from the center 

 of the tray where the wire pierces it ; j, thin piece of board holding the parts 

 of the balance in position ; k. the block of wood holding tlie knife handle at 

 proper level ; 1, darning needle serving as a pointer as the pencils oscillate in 

 weighing; m, pin marking the position of the head of the needle when the trays 

 are properly balanced before and at the close of weighing; n, "rider," or wire 

 staple, so placed as tQ balance the trays when empty ; _o, series of selected BB 

 shots used as weights; whole ones are flattened to prevent rolling ; others are cut 

 into halves, quarters, eighths, and sixteenths, and selected with reference to the 

 equality of their weights. 



