CONTROL OF SAPONIFIED SOLUTIONS 3 
for use in the field and consequently the congealing point should 
lie below an appropriately chosen temperature. Instead of form- 
ing a uniform jelly with the cresol, the soap sometimes tends to sepa- 
rate in isolated particles which first render the solution turbid and 
later rise to the surface, where they become agglomerated into a 
mass of separated soap. Such a condition is objectionable, because 
the uniformity of the preparation is lost and is not readily recovered 
again in commercial containers handled under field conditions after 
the temperature has risen. The necessity for avoiding separation 
at low temperatures will operate to restrict the manufacturer with 
respect to both the maximum percentage of soap in his product and 
the nature of the fatty acids constituting the soap; possibly, too, 
with respect to the nature of the alkali. 
SUFFICIENTLY RAPID RATE OF SOLUTION 
Varying primarily with the proportion of soap and its nature, 
there is a considerable tendency for a saponified cresol solution to 
lose its original fluidity when added to water and to form masses 
or particles of jelly. Such a material may be completely soluble, 
but ma} 7 dissolve so slowly, especially in cold water, that it becomes 
objectionable in the field. The presence of jelly particles may easily 
escape the notice of the operator, and the application of such a sus- 
pension in place of a uniform solution might conceivably cause 
serious injury to animals, particularly to their eyes, and in general 
could not be trusted to exert uniformly reliable germicidal or insecti- 
cidal effects. The necessity for a sufficiently rapid rate of solution 
has been the chief reason why the soaps of so few fats or oils have 
been considered appropriate for use in making saponified cresol solu- 
tions. 
SOLUBILITY 
A saponified cresol solution should form a practically clear solu- 
tion with distilled water. A few particles of solid matter are prob- 
ably of no significance, but there should be no globules present, how- 
ever minute. Such globules may consist of highly concentrated 
cresol and are objectionable for much the same reasons as apply to 
masses of undissolved jelly. Their presence may be due (1) to the 
use of an impure cresol which contains a considerable proportion of 
hydrocarbons, (2) to a high proportion of high-boiling phenolic 
homologues in the commercial cresol, (3) to a high percentage of 
total phenols, (4) to unsaponified fatty oil or fatty acids, or (5) to a 
low proportion of soap. A requirement for the absence of globules 
on dilution therefore automatically restricts the manufacturer in all 
these particulars. 
THE PERCENTAGE OF NEUTRAL SOAP 
Although the germicidal and insecticidal efficiency of cresol is 
very likely modified by admixture with various proportions of 
various kinds of soaps, it must be presumed that the only real reason 
for the presence of soap is to render the cresol more soluble. Cer- 
tainly the addition of soap is never recommended for solutions of 
benzophenol, a homologue already sufficiently soluble. As noted, 
specifications relative to resistance to low temperature, and to rate 
