456 
E. H. TOOLE AND W. E. TOTTINGHAM 
Table i 
Data of Plant Yields and Analyses of Solutions for Cultures of Twenty-one Days' Duration in Knop's 
Solution Variously Treated 
Solid Added 
Yield of Dry 
Tops, per 
Plant 
Yield of Dry 
Roots, per 
Plant 
Length of 
Fresh Roots 
Hydrogen-ion Concen- 
tration 
Phosphorus 
in Solution, 
per Liter 
Calcium in 
Solution, 
per Liter 
Kind 
of 
Plant 
Kind 
Amt. 
Sepa- 
rate 
Aver- 
Sepa- 
rate 
Aver- 
Per 
Aver- 
Uncropped 
after 4 Days 
Cropped, 
after Last 4 
Days Growth 
Uncropped, 
after 4 Days 
Uncropped, 
after 4 Days 
Cul- 
ture 
age 
Cul- 
ture 
age 
Cul- 
ture 
age 
Per 
Solu- 
tion 
Aver- 
age 
Per 
CuU 
ture 
Aver- 
age 
Per 
Solu- 
tion 
Aver- 
age 
Per 
Solu- 
tion 
Aver- 
age 
Barley 
None 
Fe(0H)3 
Fe(0H)3 
HaSiOs 
HaSiOs 
Carbon 
black 
Carbon 
black 
grams 
0-5 
2.5 
-0.5 
2.5 
0.5 
2.5 
milli- 
grams 
97 
117 
137 
149 
175 
146 
73 
75 
116 
88 
86 
59 
61 
51 
milli- 
grams 
107 
142 
162 
•7 A 
74 
102 
72 
56 

milli- 
grams 
36 
50 
34 
37 
43 
39 
40 
44 
59 
50 
40 
29 
31 
25 
milli- 
grams 
43 
36 
41 
42 
55 
34 
28 
milli- 
meters 
215 
215 
240 
260 
200 
220 
165 
TAT 
191 
178 
162 
186 
154 
159 
166 
milli- 
meters 
215 
250 
210 
170 
170 
170 
162 
Pjf 
6.0 
6.0 
7-4 
7.4 
6.0 
6.0 
5-7 
5-7 
6.0 
7.4 
6.0 
5.7 
Ph 
7.4 
7-5 
7.4 
6.9 
7.4 
7.5 
7.4 
6.9 
milli- 
grams 
86 
88 
4.0 
5-0 
94 
84 
82 
90 
milli- 
grams 
87 
4-5 
89 
86 
milli- 
grams 
798 
815 
616 
614 
812 
790 
819 
825 
milli - 
grams 
806 
615 
801 
822 
Peas 
None 
Fe(0H)3 
Fe(0H)3 
H2Si03 
H2Si03 
Carbon 
black 
Carbon 
black 
0.5 
2.5 
0.5 
2.5 
0.5 
2.5 
86 
96 
99 
109 
141 
88 
71 
56 
96 
116 
88 
64 
104 
115 
91 
104 
115 
64 
106 
76 
109 
31 
33 
29 
29 
38 
29 
29 
22 
38 
48 
33 
36 
32 
40 
32 
29 
33 
26 
43 
34 
36 
167 
153 
166 
166 
166 
154 
114 
108 
135 
139 
158 
146 
140 
140 
160 
166 
160 
III 
137 
152 
140 
* The Pjj value is the number representing the logarithm of the hydrogen-ion concentration. 
The actual hydrogen-ion concentration is higher as the Pji value decreases. Neutrality is expressed 
by a P// value of 7.0. The limiting Pjf values of this table, 5.7 and 7.5, represent hydrogen-ion 
concentrations of 2 X lo"^ normal and 0.32 X io~^ normal respectively; or 2 grams and 0.032 
grams of hydrogen ions per million liters respectively. 
