124 Report OF THE CHEMIST OF THE 
a more complete knowledge of the composition of the varieties 
of whale-oil soap found in the market. 
It may be stated here at the outset that many commercial 
whale-oil soaps contain no whale-oil proper, but the term “ whale- 
oil” is applied to any kind of fish-oil soap, and the oil of such 
fish as the menhaden has come to be largely used as a substitute 
for more expensive oils. 
Before taking up our chemical study of soaps, we will call 
attention, in passing, to the reason why fish-oil soaps are used 
as extensively as they are. Destructive insects cause injury in 
two ways, first by destroying portions of the foliage by direct 
biting or cutting out pieces of the leaves, and, second, by suck- 
ing the juices of the plant. The insects causing injury in the 
first way are readily killed by applying insect poisons to the 
foliage. The sucking insects, among which the San José scale 
and plant lice are the most common, are not killed by the appli- 
cation of ordinary insect poisons. They can be killed only by 
what is known as a “contact remedy,” which is either a fluid 
that penetrates the spiracles or breathing holes, filling them up 
and thus causing death, or is a water-solution of some substance, 
which, when the water evaporates, remains as a thin coating 
over the insects, thus covering the spiracles and preventing 
breathing. Whale-oil soap is a contact remedy of the second 
kind and, owing to the rapid spread in recent years of plant 
lice and scale, has become most important on account of its very 
extended application, being used probably more than any other 
contact remedy. 
It is supposed by some that whale-oil soaps possess in them- 
selves some peculiar value for destroying insects, and this opinion 
might appear to be justified by the extreme offensiveness of the 
odor, but as a matter of fact any good soap possesses just as 
much value for this purpose, the preference shown for fish-oil 
soaps being due solely to their relative cheapness. 
THE COMPOSITION OF WHALE-OIL SOAPS. 
There were collected for analysis nine different brands of com- 
mercial whale-oil soap, some being obtained directly from manu- 
facturers, Some by private purchases and others from supplies on 
hand at the Station. 
