26 BULLETIN 309, U. S. DEPARTMENT OF AGRICULTURE. 
which can be maintained accurately at a constant temperature and 
relative humidity, conditions which are absolutely essential to com- 
parative and absolute paper testing. 
The sample designated as No. 41 was manufactured from the com- 
bined pulps of cooks Nos. 7, 8, 9, and 10, and the sample designated 
as No. 76 was manufactured from the combined pulps of cooks Nos. 
11, 12, 13, and 14. The report of the Leather and Paper Laboratory 
on these samples is shown in Table VIII. 
Table VIII. — Physical properties of six paper samples made from zacaton pulp, accord- 
ing to tests conducted by the Leather and Paper Laboratory of the Bureau of Chemistry. 
L. and 
P. No. 
Mark 
Xo. 
Ash. 
Weight, 
25x38, 
500. 
Bursting strength. 
Strength 
factor, 
per wt., 
25x38. 
Thick- 
ness. 
Folding endur- 
ance. 
Folding factor. 
Aver- 
age. 
Maxi- 
mum. 
Mini- 
mum. 
Trans- 
verse. 
Longi- 
tudinal. 
Trans- 
verse. 
Longi- 
tudinal. 
Per ct. 
Lis. 
Pts. 
Pts. 
Pts. 
-30612 
41 
19.5 
51.0 
28.0 
29.0 
27.0 
0. 55 
36 
27 
42 
0.53 
0.82 
30613 
41 
19.4 
49.5 
25.5 
27.0 
24.0 
.52 
34 
25 
39 
.51 
.79 
30614 
41 
19.2 
51.0 
27.5 
29.0 
26.0 
.54 
37 
38 
35 
.74 
.69 
30615 
76 
22. 4 
52.5 
13.0 
14.0 
12.0 
.25 
40 
4 
3 
.08 
.06 
30616 
76 
22.5 
57.0 
14.0 
14.0 
14.0 
.25 
3S 
4 
3 
.07 
.05 
30617 
76 
21.4 
52.5 
13.5 
14.0 
13.0 
.26 
39 
3 
3 
.06 
.06 
Sample No. 41 contains the ash specified for a coated paper, namely, 
20 per cent, although some uncoated book papers carry nearly this 
quantity. Practice varies in the different mills, some using more 
filler than others for the same general grade of paper. This sample 
shows a strength factor, which is the bursting strain divided by 
the ream weight, which is higher than that specified for a first-grade 
machine-finish printing paper, although the ash is four times that of 
this grade. The folding factor is likewise higher than is specified for 
a first-grade machine-finished printing paper. 
Sample Xo. 76, according to the same classification, would fall below 
the fourth-grade machine-finish printing paper. 
It should be noted here, however, that at the time the specifications 
of Report No. 89 were drawn up, the chief object was to secure better 
papers in general for the use of the United States Government. The 
specifications, therefore, are somewhat different and more rigorous 
than would have been the case had it been the intention to apply 
them to the general run of commercial papers. 
According to present commercial usage, sample No. 41 would be 
regarded as much better than a first-grade machine-finish printing 
paper and No. 76 would be classed as a second-grade machine-finish 
printing paper 
