oo SOO SE _ _O_ONRRSSFS 
SCIENCE AND INDUSTRY. 
hard soap, thus converting the active parts of the spray into a curd 
and so reducing or destroying its value. The compositions of soaps 
themselves, of water available for mixing sprays, and the spray 
compounds, all vary so much in composition that many conflicting 
statements have been made as to the results obtained with various 
mixtures containing soap, lead arsenate, lime sulphur, &c. The 
grower should buy the best brand of which particulars are obtain- 
able; should seek advice, and should learn to make certain tests for ~ 
himself. The preparation of sprays should be carried out with some 
intelligence, and not left entirely to rule-of-thumb methods. 
Oil Emulsions. 
Many mineral oils are used as insecticides, practically always 
in the form of emulsions with soap, though a Woburn formula uses 
copper sulphate, limewater and kerosene, and no soap. The use of 
kerosene and soap as an insecticide, with good wetting powers 
when sprayed with considerable pressure, is well known. There 
should be plenty of free soap in the mixture, e.g., for a summer 
spray— ; 
100 gallons of wash contain 1 to 2 gallons kerosene and 
10 lbs. of soft soap; other oils such as red oil “ Miscible 
oils” and various “distillate oils” are used, especially 
for certain citrus scales, and for apple woolly aphis, &e. 
When preparing emulsions it is essential to see that a proper emul- 
sion is formed, and that it is vigorously agitated right to the end 
of the spraying, or to the emptying of the container. If the agita- 
tion ceases, and the emulsion has not been well made, there is a 
tendency for the oil to separate out, and as it floats to the surface 
the last spraying material in the container may be almost pure oil. 
This is dangerous to the trees, and has been the cause of frequent 
trouble with careless growers. Such oil sprayed on the trees has 
not only killed the bark, but has run down the trunks, and, being 
absorbed by the soil, has produced a rot, like a collar rot, round the 
trunk of the tree. 
Spraying is an operation that requires careful attention to directions 
and painstaking, patient execution. Poorly done, the benefits may be 
nil, or damage may result from the chemicals used. A spraying solution 
may be effective or ineffective, according to the force with which it is 
applied, its fineness and the liberality in the quantity used. When the 
spray accumulates in drops or drips, or runs off, too much is present; 
on the other hand every part of the plant surface should be covered 
with a film of spray. Satisfactory results can be secured only by the 
use of proper equipment, which includes the following :— 
-4. A nozzle of suitable and efficient construction. 
2. The provision of adequate pressure to produce the required 
types of spraying, to reach as high as necessary, and in the 
particular direction required, e.g., upwards, underneath 
the plants. soe Fs 
- 8: A type of machine suited to the size and conditions of the 
plantation to be sprayed. cia 
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