74 
need be added before using. Neither mixture should be kept more 
than one day before being used. The lime gradually precipitates the 
copper in needle-shaped and granular particles, which very quickly 
clog tbe spraying-nozzle. The copper-soda solution after a short time 
becomes wholly unserviceable on account of the granular deposit. The 
more or less rapid formation of the deposit depends on the strength of 
the solution in soda. If, for example, one uses 4J pounds sulphate of 
copper and 5| pounds of soda, the deposit takes place in eight or ten 
hours, whereas by using only 5 pounds of soda the solution remains 
serviceable for twenty-four hours or longer. 
In using the copper-lime and copper-soda preparations one should 
observe the following rules: 
(1) The lime must be reduced to a homogeneous lumpless cream. 
(2) Both the lime-cream and soda solution must be added only to a 
very dilute solution of copper sulphate. Indeed this should be so dilute 
that no subsequent addition of water will be necessary. 
(3) Although a larger amount of lime than is necessary may be added 
without injury to the foliage of the plants, yet according to the quan¬ 
tity of the lime used will be the rapidity with which the pulverulent 
precipitate is formed. Any surplus of soda will injure the foliage. 
(4) The mixture must not be stored, but used immediately after it is 
prepared. * 
If one has water handy to the field it may be more convenient and 
expeditious to prepare at the house strong simple solutions of copper 
sulphate and soda, and dilute them afterwards in the field. One may, 
for example, wet 2 pounds 3 ounces copper sulphate with 1J gallon of 
water and 2 pounds 9 ounces soda with the same quantity of water, and 
for this purpose hot water is the best. Twenty-six ounces of burnt lime 
or 5J pounds of air-slaked lime will produce 1J gallon of lime-cream. For 
the production of the final mixtures dilute 2£ gallons of the copper solu¬ 
tion to 26 gallons and add 2J gallons of the soda solution or the same 
quantity of the lime-cream. Weak mixtures act about as well as strong 
ones, and instead of 4^ pounds copper sulphate, one may use only 2 
pounds 3 ounces. In place of 5 pounds of soda, 2 pounds 9 ounces may 
be used. But where the weaker mixtures are employed, it is recom¬ 
mended to spray somewhat more copiously. 
The author has also experimented with a dry powder composed of 
10 parts copper sulphate, 10 parts burnt lime, and 100 parts calcined 
gypsum. 
Spraying with liquids is preferable to dusting with powders, be¬ 
cause in liquid form the copper is more divided and sticks longer to 
the leaves ; the effect being therefore more permanent. On the other 
hand the powder is very convenient in cases where an effective spraying 
apparatus is wanting and in situations where water is difficult to pro¬ 
cure. Moreover the powder can be applied by women $ the liquids can 
not. 
