time would be
taken up in preparing the ingredients in small quantities.
Instead, large amounts of copper sulphate should be dissolved
and large quantities of lime slacked beforehand. This may be
done as follows:

In a fifty-gallon barrel place about forty gallons of water.
Put one hundred pounds of copper sulphate in a sack and suspend
it in the water. As soon as dissolved, fill up to the
fifty-gallon mark. When well stirred, each gallon will contain
two pounds of copper sulphate. Each time some of the solution
is dipped out, the height of the remaining portion should be
marked on the inside of the barrel. Before taking more of the
solution out of the barrel, any amount of water lost by
evaporation should be made good by filling up to the mark last
made.

As soon as procured the lime should be slacked, placed in a
barrel and kept covered with an inch or two of water. In this
way it can be kept indefinitely.

To prepare Bordeaux mixture from these stock solutions, dip out
two and a half gallons of the copper sulphate solution, place
it in barrel No. 1 and dilute to twenty-five gallons. From the
slacked lime take fifteen pounds, or thereabouts, to allow for
the water it contains, reduce to a thin paste, place it in
barrel No. 2 and add water to make twenty-five gallons. Pour
the contents of barrels Nos. 1 and 2 together, as already
directed.

_Tests_: If free copper be present, severe injury may be done
to the foliage or other tender parts of the plants. Sufficient
lime should be added to neutralize it.

Dip out a small quantity in a porcelain saucer or shallow bowl,
and holding it on a level with the mouth, blow the breath
gently into it. If a thin pellicle forms on the surface, more
lime must be added. Add and test until it does not form. An
excess of lime will not hurt.

Another test is to dip the blade of a clean knife into the
mixture. If a thin film of copper forms on it after holding it
there a minute or so, more lime must be added.

Use good materials and prepare the mixtures thoroughly.

In making up the various mixtures, never use iron vessels, but
use glass, wood or crockery receptacles instead.

Strain all mixtures thoroughly into the spray pump to prevent
clogging of the pump or nozzles.