502 
Journal of Agricultural Research 
Vol. XXVIII, No. 6 
Table I.— Effect of the amount of moisture on the height of the briquette 
son 
Weight 
of wet 
briquette 
Weight 
of dry 
briquette 
Per cent 
moisture 
Height of 
briquette 
Height of 
briquette 
per gram 
of dry soil 
Norfolk fine sandy loam sofi_ 
Grams 
20.95 
Grams 
20.00 
4.8 
Milli¬ 
meters 
23.27 
Milli¬ 
meters 
1.163 
Do_ 
21.48 
19.99 
7.5 
22.75 
1.138 
Do__ 
21.99 
20.02 
9.8 
22.47 
1.122 
Do_ 
22.47 
20.03 
12.2 
22.50 
1.123 
Do__-_ 
' 
22. 75 
20.11 
13.1 
22.85 
1.136 
Marshall silt loam soil- 
20.97 
19.90 
5.4 
26.60 
1.337 
Do__ 
20.96 
19.45 
7.8 
25.03 
1.287 
Do_ 
21.96 
19.93 
10.2 
24.74 
1.242 
Do___ 
22.37 
19.82 
12.9 
23.96 
1. 210 
Do_ 
22.95 
19.99 
14.8 
23.75 
1.189 
Do_ 
23.45 
19.92 
17.7 
24.15 
1. 212 
Do____ 
23.94 
19.90 
20.3 
25.27 
1.270 
Sharkey clay soil- 
21. 78 
20.00 
8.9 
26.63 
1.332 
Do_ 
22.53 
19.93 
13.0 
24. 71 
1.240 
Do- 
23.12 
19.95 
15.9 
23.95 
1.200 
Do__ 
23. 57 
19.95 
18.1 
23.88 
1 . 196 
Do_ 
23.78 
19.92 
19.4 
24.17 
1. 213 
Do__ 
24.34 
19.94 
22.1 
25.17 
1 . 282 
Table I shows how the height of the briquette varies with the amount of 
moisture for three different soils. In order to determine the critical moisture 
content the height per gram of dry soil is plotted against the per cent moisture 
as in figure 3 and the value at the lowest point of the curve indicates the critical 
moisture content. 
Table II.— Effect of the amount of moisture on the breaking strength of the briquette 
SoU 
Moisture 
Weight 
of 
briquette 
Average 
load per 
briquette 
Load per 
gram of 
soU 
Per cent 
Grams 
Kilograms 
Kilograms 
Norfolk fine sandy loam soil___ 
4.8 
21.6 
88 
4.1 
Do__ 
7.5 
22.0 
143 
6.5 
Do___ 
9.8 
22.3 
175 
7.8 
Do _ __ _ 
12.2 
22.3 
161 
7.2 
Do____ 
13.1 
22.1 
141 
6.4 
Marshall silt loam soil_ 
5.4 
18.7 
102 
5.5 
Do-j 
7.8 
19.5 
213 
10.9 
Do_ 
10.2 
20.2 
351 
17.4 
Do__! 
12.9 
20.7 
528 
25.5 
Do_! 
14.8 
21.1 
671 
31.8 
Do_| 
17.7 
20.7 
673 
32.5 
Do.__ 
20.3 
19.8 
471 
23.8 
The curves indicate a critical moisture content for the Sharkey clay soil of 
17^ per cent, for the Marshall silt loam soil of 15£ per cent, and for the Norfolk 
fine sandy loam of 11 per cent. If greater accuracy than one-half of 1 per cent 
was desired, the briquettes were made up near the critical moisture content with 
increments of one-half of 1 per cent moisture and a new graph plotted. This 
method showed the critical moisture content for the Norfolk fine sandy loam 
soil, for example, to be at 11.3 per cent. 
Briquettes of the Norfolk and Marshall soils were made up of the same samples 
of material used in the determination indicated in Table I to determine the 
effect of the amount of moisture on the breaking strength. These results are 
shown in Table II and graphically in figure 4. In this case, since the briquettes 
