THE SAN JOSE SCALE AND ITS CONTROL. 23 
The stage at which cold water should be poured on to stop the 
cooking varies with different grades of lime. Some limes are so 
sluggish in slaking that it is difficult to obtain enough heat from them 
to cook the mixture at all, while other limes become intensely hot 
on slaking, and care must be taken not to allow the boiling to proceed 
too far. If the mixture is allowed to remain hot 15 or 20 minutes 
after the slaking is completed the sulphur gradually goes into solu- 
tion, combining with the lime to form sulphids, which are injurious 
to peach foliage. It is therefore very important, especially with 
hot lime, to cool the mixture quickly by adding a few buckets of 
water as soon as the lumps of lime have slaked down. The intense 
heat, violent boiling, and constant stirring result in a uniform mixture 
of finely divided sulphur and lime, with only a very small percentage 
of the sulphur in solution. It should be strained to take out the 
coarse particles of lime, but the sulphur should be carefully worked 
through a strainer. The mixture can be prepared in larger quantities 
if desirable, say enough for 200 gallons at a time, making the formula 
32 pounds of lime and 32 pounds of sulphur to be cooked with a small 
quantity of water (8 or 10 gallons) and then diluted to 200 gallons. 
COMMERCIAL POWDERED SULPHUR COMPOUNDS. 
Within the past: two or three years certain manufacturers have 
offered for sale, in a dry powdered condition, compounds of sulphur 
which are to be dissolved in water for the preparation of the spray. 
These compounds give promise of being satisfactory as scale washes, 
and if so, will undoubtedly meet with prompt favor with orchardists, 
since by their use there is a distinct saving in freight, and they are 
much more convenient in handling and storing. 
PETROLEUM-OIL SERIES. 
Under the heading “ Petroleum-oil series” are to be included kero- 
sene and crude petroleum, either pure or in emulsion, and the so- 
called miscible oils. 
Pure KEROSENE. 
Pure kerosene has been recommended to a greater or less extent 
for spraying trees badly infested with the scale, but it has never 
been very generally employed. There is no question of the efficiency 
of such an application in the destruction of the insects, but the great 
danger of injury to the plants precludes its general application. 
Treatments of pure kerosene should be made only to dormant trees 
and during bright days and should be applied through a nozzle with a 
very fine aperture. Only the minimum amount of kerosene necessary 
to cover the trees should be given, and care is necessary that the liquid 
does not puddle around the roots of the trees. 
