4 BULLETIN 1308, U. 8. DEPARTMENT OF AGRICULTURE 
and degree of solubility, will go far toward restricting the propor- 
tion and the nature of the soap which may be present in a saponified 
eresol solution. So long as these specifications are met it appears 
scarcely necessary to inquire further, as a matter of routine, into the 
nature of the fatty acids which may be present in a given sample or 
even to set a maximum limit on the percentage of soap, but undoubt- 
edly it is necessary to set a minimum limit. A certain margin of 
soap above the proportion barely necessary to bring the eresol into 
solution is desirable in order to provide for unforeseen vicissitudes, 
such as the use of hard water. Inasmuch as the nature of the fatty 
acids, which vary in molecular weight, appears not to demand de- 
termination, the control of the neutral soap present may be most 
fairly, as well as most conveniently, made by controlling the per- 
centage of alkali which is combined in the form of soap. 
RESTRICTION OF EXCESS ALKALI 
In addition to alkali combined as soap, an excess may be present 
owing either to faulty following of a formula or to incomplete 
saponification of glycerides. A slight excess is justifiable and 
perhaps even desirable, but above a certain proportion it becomes 
objectionable because it may render the final solution unnecessarily 
severe upon animals. Accordingly the excess alkali should be 
restricted by a maximum limit. 
PERCENTAGE LIMITS OF TOTAL PHENOLS 
The important active ingredient in saponified eresol solutions is 
the " total phenols." comprising all homologues present. In ad- 
dition to a minimum percentage limit which obviously must be set, 
a maximum limit is also desirable because animals may be poisoned 
by treatment with too strong phenolic solutions. 
PERCENTAGE LIMIT OF BENZOPHENOL 
Commercial eresol always contains benzophenol (C 6 H 5 OH), 
sometimes in large proportion. Xot only is benzophenol a much 
weaker germicide than eresol, but it is also more rapidly absorbed 
by the tissues of the higher animals and is consequently more dan- 
gerously poisonous. For both reasons it appears necessary to set a 
maximum limit to the proportion of benzophenol which may be 
present in a saponified eresol solution. 
PROPORTION OF HIGH-BOILING PHENOLIC HOMOLOGUES 
Inasmuch as the formation of globules upon dilution becomes 
increasingly more likely to occur as the boiling point of the mixture 
of phenolic homologues rises, it is justifiable to set an upper limit 
to the distillation range of the commercial eresol that may be em- 
ployed in compounding a saponified eresol solution. 
On the basis of the preceding discussion, the following skeleton 
specifications are suggested as fundamental and essential: 
(a) The product shall remain a uniform liquid when held at a temperature 
of for hours. 
(b) It shall dissolve completely in 30 parts water at a temperature of 
within minutes, affording a solution entirely free from 
globules, and not more than faintly opalescent. 
