32 OIL-FIELD WATERS IN SAN JOAQUIN VALLEY , CAL. 
stituents of the other group are of two kinds, the positive radicles or 
bases, chiefly sodium, potassium, calcium, and magnesium, and the 
negative or acid radicles, chiefly sulphate, chloride, carbonate, and 
bicarbonate. The several constituents of each kind have different 
but definite capacities for reacting with or holding in solution or 
equilibrium constituents of the other kind. The two kinds of con¬ 
stituents in a water are always in chemical equilibrium; that is, the 
sum of the reaction capacities, or “ reacting values,” of the positive 
radicles is equal to the sum of the reacting values of the negative 
radicles. 
The number of constituents to be determined and the accuracy 
with which the work is done differs with the use to which the analysis 
is to be put, but in general the following determinations are desirable: 
Sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), iron 
(Fe), aluminum (Al), sulphate radicle (S0 4 ), chloride radicle (Cl), 
nitrate radicle (N0 3 ), carbonate radicle (C0 3 ), bicarbonate radicle 
(HC0 3 ), silica (Si0 2 ), and total solids at 180° C. It is well also to 
test waters from oil fields for sulphide (S), a nonvolatile negative 
constituent, and the volatile substances hydrogen sulphide (H 2 S), and 
carbon dioxide (C0 2 ). The quantity of suspended matter and the 
quantity of organic matter also are usually determined. 
Iron and aluminum are usually precipitated and weighed together 
and reported as the oxides (Fe 2 0 3 -{-Al 2 0 3 ) in industrial analyses, and 
carbonate and bicarbonate are often not distinguished from each 
other. The laborious determination and separation of sodium (Na) 
and potassium (K) is omitted in many industrial analyses, and the 
content of these two substances together is calculated, after the acids 
and the other bases have been determined, by assuming the presence 
of sufficient sodium and potassium to complete the balance of reacting 
values between the bases and the acids. This implies, of course, that 
the determination of all the other radicles is absolutely correct, which 
is practically never the case; whatever errors are made in the deter¬ 
mination of all the other radicles are repeated and thrown together 
in the calculation of the alkalies. This practice thus conceals all 
error of analysis and makes it impossible to ascertain the accuracy 
of the analysis from the reported figures. If, on the other hand, all 
the radicles are actually determined the bases can be balanced against 
the acids and the discrepancy discovered. Even with reasonably 
careful work the unavoidable errors in determination usually amount 
to 1 per cent and may be 4 or 5 per cent. 
STATEMENT OF ANALYSIS. 
In analyzing a natural water the chemist can determine only the 
proportions of the mineral substances that it holds in solution. He 
can not determine what compounds have been dissolved, nor can he 
