34 BULLETIN 9£9, U. S. DEPARTMENT OF AGRICULTURE. 
A CCEPTANCE AND REJECTION OF MATERIAL. 
(15) Bans of acceptance or rejection. — Paving bricks shall not be judged for accept- 
ance or rejection by the results of individual tests, but by the average of no less than 
five tests. Where a lot of bricks fail to meet the required average, it shall be optional 
with the buyer whether the bricks shall be definitely rejected or whether they may be 
regraded and a portion selected for further test as provided in section 16. 
(16) Range of fluctuation. — Some fluctuation in the results of the rattler test, both 
on account of variations in the bricks and in the machine used in testing, are unavoid- 
able, and a reasonable allowance for such fluctuations should be made wherever the 
standard may be fixed. 
In any lot of paving brick, if the loss on a test computed upon its initial weight 
exceeds the standard loss by more than 2 per cent, then the portion of the lot repre- 
sented by that test shall be at once resampled and three more tests executed upon it, 
and if any of these three tests shall again exceed by more than 2 per cent the required 
standard, then that portion of the lot shall be rejected. 
If in any lot of brick two or more tests exceed the permissible maximum, then the 
buyer may at his option reject the entire lot, even though the average of all the tests 
executed may be within the required limits. 
(17) Fixing of standards. — The percentage of loss which may be taken as the stand- 
ard will not be fixed in these specifications, and shall remain within the province of 
the contracting parties. For the information of the public, the following scale of 
average losses is given, representing what may be expected of tests executed under 
the foregoing specifications: 
General 
average 
loss. 
Maxi- 
mum per- 
missible 
loss. 
Per cent. 
For bricks suitable for heavy traffic 22 
For bricks suitable for medium traffic 24 
For bricks suitable for light traffic i 26 
Per cent. 
24 
26 
28 
Which of these grades should be specified in any given district and for any given 
purpose is a matter wholly within the province of the buyer and should be governed 
by the kind and amount of traffic to be carried and the quality of paving bricks 
available. 
(18) Culling and retesting. — Where, under sections 15 and 16, a lot or portion of a 
lot of bricks is rejected, either by reason of failure to show a low enough average test 
or because of tests above the permissible maximum, the buyer may at his option 
permit the seller to regrade the rejected brick, separating out that portion which he 
considers at fault and retaining that which he considers good. When the regrading 
is complete, the good portion shall be then resampled and retested. under the original 
conditions, and if it fails again either in average or in permissible maximum, then the 
buyer may definitely and finally reject the entire lot or portion under test. 
(19) Payment of cost of testing. — Unless otherwise specified, the cost of testing the 
material as delivered or prepared for delivery, up to the prescribed number of tests 
for valid acceptance or rejection of the lot, shall be paid by the buyer. (See also 
section 23.) The cost df testing extra samples made necessary by the failure of the 
whole lot or any portion of it shall be paid by the seller, whether the material is 
finaJly accepted or rejected. 
