606 Philippine Journal of Science 1920 
TABLE 1.—Number of gram molecules of each salt required in 1 liter of 
water, to produce from 0.1 to 0.8 of a total osmotic concentration of 
approximately 0.5 atmosphere. 
Tenths of 0.5 atmosphere. Ca(H2POs) 2. | (NHa«)2SO4. K2S04. 
| Pret a i pe Se 0. 00081 0. 00081 0.00081 
aE Ss a ee ee 0. 00161 0. 00161 0. 00161 
ee eee ee 0, 00242 0. 00242 0. 00242 
PROTEGE Sas SEGRE ancl aoe: ARR * 9.00828} —s- 0.00828 0. 00323 
eat Ca yt Ra A Oh 2 eer ee a 0 SO 0. 00404 0. 00404 0. 00404 
We ae ea a es 0. 00485 0. 00485 0.00485 
Na ee Se 0. 00566 6. 00566 0. 00566 
RECREATE EERO DHSS ONE rae 7s Ie pen ee eR DE 0. 00647 0. 00647 0. 00647 
The amount of each salt needed to produce the required par- 
tial concentrations has been approximately calculated by means 
of the van’t Hoff equation for osmotic pressure. The general 
method used in such calculations is presented in detail in the 
paper by Tottingham previously mentioned. Table 1 gives the 
calculated number of gram molecules of each salt required to 
produce from 0.1 to 0.8 of the total osmotic concentration of 
approximately 0.5 atmosphere in 1 liter of water. The cul- 
ture medium used was composed of saturated soil with water 
standing to a depth of about 3 centimeters on the surface, and 
occupied a volume of approximately 19 liters. Accordingly, the 
values given in Table 1 were multiplied by 19 to obtain the 
amount of each salt required for each of the thirty-six cultures 
of these tests. The values thus calculated are shown in Table 
2, where they are expressed both in terms of gram molecules 
and in terms of grams, for each of the salts. 
TABLE 2.—A mount of each salt, expressed in grams and in gram molecules, 
that was added to the 19 liters of water-saturated soil of each culture. 
ee oa 
Tenths of 0.5 atmosphere. Ca(H2PO4)2. (NHa) 2804. | _ KeSO«. 
Be ESE 
gm. mol.| gm.a |gm.mol,| gm. | gm.mol.| gm. 
, RSE pai crea 0.0154 3.60| 0.0154 2.03 | 0.0154) 2.68 
BS et oe is 0. 0307 7.19| 0.0807 4.05 | 0.0307} 5.35 
as gk a el oe 0.0461 10.78 | 0.0461 6.08} 0.0461| 8.02 
Risin sae dcastbii wih ic tic ge 0.0614| 14.87) 0.0614 8.11 0.0614} 10.70 
OOS 9 SEONG os Se ea ie bene 0.0768 17.97 | 0.0768 10.14 | 0.0768 | 13.38 
Oo a ee 0.0922| 21.57| 0.0922 12.16 | 0.0922 | 16.05 
omen MERE Ae See ore | 9.3075| 25.15} 0,1075| 14.19] 0.1075] 18.78 
ipo nh eee 0.1228! 28.75 | 0.1228|  16.22| 0.1228 gos 
® Grams of the anhydrous salt. 
