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BULLETIN 949, U. S. DEPARTMENT OE AGRICULTURE. 



set has been acquired when the pat will bear without appreciable indentation, the 

 Gillmore needle one twenty-fourth inch in diameter, loaded to weigh 1 pound. In 

 making the test, the needles shall be held in a vertical position, and applied lightly 

 to the surface of the pat. 



TENSION TESTS. 



(51) The form of test piece shown in figure 13 shall be used. The molds shall be 

 made of noncorroding metal and have sufficient material in the sides to prevent 

 spreading during molding. Gang molds when used shall be of the type shown in 

 figure 14. Molds shall be wiped with an oily cloth before using. 



J 



(a) Pot with top surface flattened for determining time of setting by Gillmore method. 



•W///////////////////////////^^^^ 



(b) Gillmore needles. 

 Fig. 12. 



(52) The sand to be used shall be natural sand from Ottawa, 111., screened to pass a 

 No. 20 sieve and retained on a No. 30 sieve. This sand may be obtained at a cost of 2 

 cents per pound, f. o. b. cars, Ottawa, 111. 



(53) This sand, having passed the No. 20 sieve, shall be considered standard when 

 not more than 5 grams pass the No. 30 sieve after one minute continuous sieving of a 

 500-gram sample. 



(54) The sieves shall conform to the following specifications: 



The No. 20 sieve shall have between 19.5 and 20.5 wires per whole inch of the warp 

 wires and between 19 and 21 wires per whole inch of the shoot wires. The diameter 

 of the wire should be 0.01G5 inch and the average diameter shall not be outside the 

 limits of 0.0160 and 0.0170 inch. 



The No. 30 sieve shall have between 29.5 and 30.5 wires per whole inch of the warp 

 wires and between 28.5 and 31 .5 wires per whole inch of the shoot wires. The diameter 

 of the wire should be 0.0JJ0 inch, and the average diameter shall not be outside the 

 limits 0. 0105 to 0.0115 inch. 



