FORMS FOE SPECIFICATIONS, ETC., FOE EOAD MATERIALS. 



31 



When the material has a specific gravity below 2.20 a total weight of 4,000 

 grams instead of 5,000 grains shall be used in the abrasion test. 



(3) Toughness Test, Stone: United States Department of Agriculture Bulle- 

 tin 347, page 15. 



(4) Haedness Test, 1 Stone and Stone Block : United States Department of 

 Agriculture Bulletin 347, page 10. 



(5) Specific Gravity and Absorption Tests, Stone: 



The apparent specific gravity is obtained by weighing the water displaced 

 by a sample of the material weighing approximately 1,000 grams, broken into 

 pieces about 11 inches in diameter. (The vessel used is shown in figure 1.) 



21 Galvanized 











Iron < 







3 U. * 







Note: N 

 lower ei 

 to preve 



otch is filed across 

 id of spout i/g£' (2°) 











, 



nt drip. ==z _- zL --- 





r 





i "brass pipe, 2i "long 





\ 



800 cc 

 beaker 



\ J 



> 

 ( 











i I 



1 1 



\Three lugs soldered on) 

 bottom vymmetrically. 



Fig. 1. — Vessel used in making specific-gravity and absorption tests. 



It consists of a galvanized-iron cylinder closed at one end, and measuring 

 5 inches in diameter by 8 inches high. A brass spout \ inch in diameter is 

 soldered into the side of the cylinder, 6 inches from the bottom. The spout 

 is inclined at an angle of 2° with the horizontal and is 1\ inches long. A 

 notch is filed across its lower end, as shown, to stop the drip from the dis- 

 placed water. In determining the specific gravity, the dried and cooled 

 sample is weighed to the nearest 0.5 gram and immersed in water for 24 

 hours. The pieces are then individually surface-dried with a towel, the sample 

 reweighed, and immediately placed in the cylinder, which has been previously 

 filled to overflowing with water at room temperature. 



The weight of water displaced by the sample is used to calculate its apparent 

 specific gravity. 



1 It is recommended that the laboratories cooperate with the view of devising an im- 

 proved method for the determination of the hardness of rock, especially in regard to the 

 character of the abrasive used. 



