28 BULLETIN 049, TJ. S. DEPARTMENT OF AGRICULTURE. 
felt or broad wickiiig 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 determing 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. 
THE SELECTION OF SAMPLES FOT? 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 his judgment, to select brick representing the average of the lot. Xo 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 
10,0.00 provided that 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 
