34 
BULLETIN 1452, U. S. DEPABTMENT OF AGEICUL1UEE 
loss are all dependent upon a few more fundamental properties of 
the colloid, such as size, structure, and chemical nature of the par- 
ticles. A precise knowledge of these more fundamental properties 
is lacking, but an idea of the relationships between the properties 
given in the preceding pages may be gained from the manner in 
which variations in one property in a series of soil colloids parallel 
variations in another property. This is shown in Table 19. 
Table 19. — Degree to which different soil colloids possess certain properties, as 
shown ~by relative values 
Kind of colloid 
I 1 
Recipro- 
cal of .j„ nrn 
average Hear of '\?*™R' 
diameters wettine vw 
of ~~ NH * 
particles 
Adsorp- 
tion of 
H 2 
vapor 
Imbibed 
water 
Moisture Volume 
equiva- increase 
lent in water 
Fallon 
1 78 100 100 
100 90 99 
60 76 67 
18 37 25 
49 25 10 
17 19 25 

100 
86 
63 
50 
9 
26 

100 100 100 
Sharkey 
80 ' 55 46 
Marshall 
52 17 23 
S assaf ras 
20 23 
| 3 7 
Norfolk 
4 1 
Susquehanna 
35 
! 
Recipro- 
cal of 
Methyl- 
Kind of colloid 
Volume 
of floe 
Viscosity 
of 2 per 
cent sols 
concen- 
tration 
required 
to give 
ene blue 
required 
to render 
isoelec- 
Exchange- 
able 
Ca+Mg+ 
K+Na 
PH 
Average 
of prop- 
erties 
viscosity 
tric 
of 1.9 
Fallon 
100 
100 
100 
100 
100 
100 
98 
Sharkey 
81 
10 
54 
85 
60 
00 
69 
Marshall 
28 
52 
54 
63 
44 
62 
51 
Sassafras 
7 
100 
65 
12 
14 
14 
30 
Huntinwton 
19 
f 

23 
19 
1 
N. D. 

59 

15 
Norfolk.... 
9 
Susquehanna 
71 
86 


10 
19 
1 As pointed out on p. 5, there is considerable evidence that the Fallon particles are smaller than 
those of the Sharkey colloid. If this is so, the figure for the Fallon should be 100 and the figtires for the 
other colloids somewhat less than those in this column. 
In Table 19 the degree to which the colloids possess various prop- 
erties is shown by relative values,' 22 to facilitate comparison, since the 
properties were expressed in many different units in the preceding 
pages, and the colloids vary more widely in some properties than in 
others. The basis of the relative values in the case of each property 
is the range in the property exhibited by the seven colloids which 
were used in most comparisons. The difference between the highest 
and lowest values found for the seven colloids is taken as 100 for 
each property. For instance, the adsorptive capacity of the colloid 
adsorbing most water is assigned a value of 100: the adsorptive 
capacity of the colloid adsorbing least water is taken as 0; and the 
adsorptive capacities of the other five colloids are expressed propor- 
tionally to this variation of 100. This method of expression gives a 
uniform basis of values for different properties and makes the ampli- 
22 The relative specific gravities of the different colloids were omitted from this table, 
since they showed so little correlation with other properties that their inclusion would 
have tended to obscure the correspondence obtaining between other properties shown in 
subsequent calculations. 
