June, ’18] 
SCIENTIFIC NOTES 
341 
placed in all latrines, dormitories, cook-houses and stores and are con¬ 
stantly renewed. 
That the measures adopted have proved effective is well illustrated 
by the fact that on several occasions the Oval of the show grounds has 
been used for patriotic functions attracting thousands of the public, 
and yet on no occasion has the least inconvenience been caused by the 
close proximity of the large number of animals in the Depdt, nor by the 
thousands of tons of stored manure. 
Scientific Notes 
A Promising New Contact Insecticide. From the results of a series of experi¬ 
ments, it has been determined that the most efficient contact insecticides must be of 
an oily or soapy nature. Based upon these observations, a new contact insecticide 
has been made by the formation of a soap or soap-like salt by the union of nicotine and 
oleic acid. This chemical is nicotine oleate. It dissolves in soft water forming a 
soapy solution which may be used to emulsify an animal, vegetable or mineral oil. 
The following experiments give an idea of its value. First, Nicofume, containing 
40 per cent of nicotine diluted with water to give a nicotine content of 1 part in 1,000 
of water, killed 95 per cent of the chrysanthemum aphis. Nicotine oleate, diluted to 
give 1 part of nicotine in 1,500 parts of water, killed 96 per cent, while diluted to 1 
part of nicotine in 4,500 parts of water killed 63 per cent. 
Second, Nicofume, diluted to a nicotine content of 1 part in 1,500 with 2 parts of 
laundry soap added, killed 93 per cent of the chrysanthemum aphis, while the nicotine 
oleate with a nicotine content of 1 to 2,250 killed 97 per cent. 
Third, Nicofume in aqueous solution does not kill mealy-bugs. Nicotine oleate 
used at the rate of 1 to 500 will kill a few mealy-bugs and a few egg clusters. Two 
per cent of a vegetable, animal or mineral oil emulsified in the nicotine oleate solution 
will kill mealy-bugs and their eggs. An emulsion containing 1 part of nicotine in 
500 parts of water with 2 per cent kerosene killed 79 per cent of the adult mealy-bugs 
and their older larvae, 98 per cent of the eggs, and 98 per cent of the young larvae. 
Fourth, Preliminary experiments have shown that about 85 to 90 per cent of the 
soft scale on greenhouse plants may be killed using nicotine oleate at a dilution of 1 
part of nicotine to 500 parts of water. 
Fifth, Preliminary experiments have shown that adults and larvae of the white 
fly may be killed at the same dilution as used for the soft scale. 
All experiments mentioned were conducted under laboratory conditions, care 
being taken to hit all the insects used in the experiments. Under field conditions it 
may be necessary to use a higher percentage. Nicotine oleate being nonvolatile it is 
more necessary to insure striking all insects than in the use of a volatile compound 
like nicofume. 
Nicotine oleate may be made directly from any nicotine preparation containing 
free nicotine. Two and one-half parts of a 40 per cent nicotine solution unites with 
If parts of commercial oleic acid or red oil. Four and one-fourth parts of this soap 
will then contain 1 part of nicotine or will equal 2 \ parts of the 40 per cent nicotine 
solution. Two and one-half quarts of 40 per cent nicotine solution costing about 
$7.00 can be mixed with If quarts of commercial oleic acid costing about 90c. making 
If gallons of nicotine oleate. For spraying to control plant lice, where a gallon of a 
