Nov. 21 ,1916 ' Nicotine-Sulphate and Fish-Oil-Soap Sprays 
399 
respectively. The proportional efficiency of the sprays proved to be 
similar for each species. The efficiency of the sprays was determined 
by counting the number of live insects on a portion of the plot previous 
to the application of the sprays, and again determining the number two 
hours after treatment. The experiments were performed on 27 one- 
twentieth-acre plots. Peas were sprayed five times, spinach and straw¬ 
berries once. The wetting powers as well as the nicotine content of the 
solutions were determined. 
(3) When more than 4 pounds of soap were used with 10 ounces of 
nicotine sulphate to 50 gallons of water, there was a loss of both wetting 
power and efficiency. 
(4) When more than 8^ ounces of nicotine sulphate were combined 
with 5 pounds of fish-oil soap to 50 gallons, a loss occurred in both the 
wetting power and the efficiency. 
(5) When nicotine sulphate was used in quantities up to 10 ounces, to 
a i-to-50 fish-oil-soap solution, none of the resultant sprays had an effi¬ 
ciency of more than 75 per cent. Also, when fish-oil soap was used alone 
in quantities not exceeding 8 pounds to 50 gallons, the highest efficiency 
of any of the formulas was only a fraction over 75 per cent. 
(6) It was found that the nicotine content of the solutions remained 
the same irrespective of the amount of soap used. 
(7) The loss of efficiency due to increasing the concentrations of the 
solutions is probably caused by a loss of both wetting power and insecti¬ 
cidal value of the soap. 
(8) The loss of wetting power which occurs when the concentration 
of the solutions is increased has a stronger tendency to reduce the effi¬ 
ciency of the subsequent solutions, if the original solution has an effi¬ 
ciency of 85 per cent or more, than it does if the original efficiency is 
below 75 per cent. 
(9) The actual importance of wetting power is difficult to determine 
in this case, as the fish-oil soap has insecticidal properties in itself. 
Where the wetting power is affected, it is probable that the soap is also 
broken down sufficiently to lose some of its value as an insecticide; hence, 
both factors must be considered as the cause of the loss of efficiency of 
some of the more concentrated mixtures. 
