28 BULLETIN 94&, U. S. DEPARTMENT OF AGRICULTURE. 



felt or broad wicking kept wet. The bottom of the moist closet should be covered with 

 water. The interior of the closet should be provided with nonabsorbent shelves, on 

 which to place the test pieces, the shelves being so arranged that they may be with- 

 drawn readily. 



(60) Unless otherwise specified all test pieces, immediately after molding, shall be 

 placed in the moist closet for from 20 to 24 hours. 



(61) The briquettes shall be kept in molds on glass plates in the moist closet for at 

 least 20 hours. After 24 hours in moist air the briquettes shall be immersed in clean 

 water in storage tanks of noncorroding material. 



(62) The air and water shall be maintained as nearly as practicable at a temperature 

 of 21° C. (70° F.). 



18. TESTS FOR PAVING BRICK. 



(A. S. T. M. Standard Method, Serial Designation: C 7-15.) 



The quality and acceptability of paving brick, in the absence of other special tests 

 mutually agreed upon in advance by the seller on the one side and the buyer on the 

 other side, shall be determined by the following procedure: 



I . The rattler test for the purpose of determining whether the material as a whole 

 possesses to a sufficient degree strength, toughness, and hardness. 



II. Visual inspection for the purpose of de terming whether the physical properties 

 of the material as to dimensions, accuracy, and uniformity of shape and color are in 

 general satisfactory, and for the purpose of culling out from the shipment individually 

 imperfect or unsatisfactory brick. 



The acceptance of paving brick as satisfactorily meeting one of these tests shall not 

 be construed as in any way waiving the other. 



I. THE RATTLER TEST. 

 i 



THE SELECTION OF SAMPLES FOK TESTS. 



(1) Place of sampling. — In general, where a shipment of bricks involving a quantity 

 of less than 100,000 is under consideration, the sampling shall be done at the factory 

 prior to shipment. Bricks accepted as the result of test prior to shipment shall not be 

 liable to subsequent rejection as a whole, but are subject to such culling as is provided 

 for under Part II, visual inspection. 



(2) Method of selecting samples. — In general, the buyer shall select his own samples 

 from the material which the seller proposes to furnish. The seller shall have the right 

 to be present during the selection of a sample. The sampler shall endeavor, to the best 

 of Iris judgment, to select brick representing the average of the lot. No samples shall 

 include bricks which would be rejected by visual inspection, as provided in Part II, 

 except that where controversy arises whole tests may be selected to determine the 

 admissibility of certain types or portions of the lot having a characteristic appearance 

 in common. In cases where prolonged controversy occurs between buyer and seller 

 and samples selected by each party fail to show reasonable concurrence, then both 

 parties shall unite in the selection of a disinterested person to select the samples, and 

 both parties shall be bound by the results of samples thus selected. 



(3) Number of samples per lot. — In general, one sample of 10 bricks shall be tested 

 for every 10,000 bricks contained in the lot under consideration; but where the total 

 quantity exceeds 100,000 the number of samples tested may be fewer than 1 per 

 10,000 provided 1hat they shall be distributed as uniformly as practicable over the 

 entire lot. 



(4; Shipment of samples. — Samples which must be transported long distances by 

 freight or express shall be carefully put up in packages holding not more than 12 

 bricks each. When more than 6 bricks are shipped in one package, it shall be so 

 arranged as to carry two parallel rows of bricks side by side and these rows shall be 



