32 
Journal of Agricultural Research 
Vol. XXIII, No. » 
The mineral component of the osmotically active material of the sap 
was determined by evaporating the sap, igniting the residue, and restor¬ 
ing the original volume with distilled water. The data in Table I clearly 
show that where no potash was applied to the soil much the greater pro¬ 
portion of the osmotic concentration represents soluble organic material, 
probably carbohydrate, whereas with increasing quantities of potash 
salts applied to the soil this relationship is reversed, the mineral compo¬ 
nent becoming the more important. The ehlorid, moreover, contributes 
more to the osmotic concentration of the sap than does the sulphate. 
These observations seem to be in line with the view which has long been 
held that lack of an adequate supply of potash tends to cause congestion 
or accumulation of carbohydrate in the tissues of the leaf. 
The saps (in io cc. portions) from the general fertilizer test plots col¬ 
lected on July 24 and those from the special potash plots collected on 
July 23 were employed in studying the quantity and character of the 
ash contained in the sap, as influenced by the sulphate and the ehlorid 
of potassium. The total ash was determined by ignition and the soluble 
ash by extracting the ignition residue with successive portions of hot 
distilled water aggi egating a volume of 100 cc. The alkalinity of the 
soluble and insoluble portions of the ash was determined by titration, 
using methyl orange as indicator. The calcium in the insoluble ash was 
determined gravimetrically. The results are presented in Table II. 
Table II. —Character of the ash of tobacco sap as affected by the ehlorid and the 
sulphate of potassium 
Fertilizer treatment of tobacco. 
Total 
ash. 
■! Soluble 
ash. 
Insolu¬ 
ble ash. 
Alkalin¬ 
ity of 
soluble 
asb.o 
Alkalin¬ 
ity of 
insolu¬ 
ble ash.« 
CaO in 
insolu¬ 
ble ash. 
Regular fertilizer test plots: 
Gr. 
Gr. 
Gr. 
Gr. 
N+P.... ? 
c. 1694 
:°- 0538 
0.1156 
0. 6 
22. 4 
N 4 -P+ 8 o pounds K a O ; as sul- 1 
phate.! 
. 1816 
. 1^20 
. 0496 
1. 1 
10.5 
N+P+160 pounds K 2 0 , as sul- i 
phate.! 
. 2219 
• 1748 
.0471 
11. 4 
9.4 
N+80 pounds K 2 0 , as sulphate, .j 
• 1497 
* I167 
•0330 
11. 7 
7.2 
P+80 pounds K 2 0 , as sulphate.. 
. i8ci 
• 1531 
. 0270 
10.3 
5-0 
Special potash test plots: j 
N+P.| 
. 1999 
.O45O 
• 1549 
4. 1 
32.6 
0. 090- 
N+P+24 pounds K 2 0 , as ehlorid. j 
• 15 28 
•0574 
• 0954 
•7 
20. I 
•°55 
N+P+24 pounds K 2 0 , as sul- ! 
phate.i 
. 1822 
. 0707 
.1115 
7-3 
2 3-5 
. 061 
N+P+80 pound K a O, as ehlorid.. 
• 1595 
. 1228 
.0367 
.6 
8.6 
. 020 
N+P+80 pounds K 2 0 , as sul¬ 
phate ... 
. 1661 
. 1202 
• ° 4 S 9 
10. 7 
10.3 
. 028- 
• Expressed in cubic centimeters of N/io acid required for titration. 
Both the chloridfand the sulphate of potash produce marked increases 
in the soluble portion of the ash of the sap and equally as large decreases 
in the insoluble portion. There is no marked difference in this respect 
in the action of the two salts, perhaps indicating that approximately^ 
equal quantities of potash are absorbed by the plant from these two 
sources when the rates of application to the soil are equal. That the 
effects of the two salts on the metabolism of the plant are different,, 
however, is clearly shown by the alkalinity of the soluble and insoluble 
