371 
SUMMARY. 
(1) Copper sulphate may be dissolved very easily by suspending the 
crystals in a loosely woven cloth or basket near the top of a vessel filled 
with water or by conducting steam into the vessel through a pipe. 
(2) It is most convenient to make up a stock solution containing 2 
pounds of copper sulphate to the gallon. 
(3) Only the best freshly burned stone lime should be used in mak¬ 
ing Bordeaux mixture. When slaked it should be free from coarse 
granules. 
(4) Stock milk of lime containing the equivalent of 2 pounds of 
unslaked lime to the gallon may be readily prepared. 
(5) The method of testing Bordeaux mixture with a solution of potas- 
sium ferrocyanidc to determine when enough lime has been added, is 
difficult to apply in practice unless stock milk of lime be used. 
(6) The color of the mixture is a good indication of its composition. 
When properly made it is of a deep sky-blue color. Such a mixture 
contains a slight excess of lime, and on standing a few moments in a 
broad, open vessel is covered with a thin pellicle of calcium carbonate. 
The clear liquid left after settling gives no brown color with potassium 
ferrocyanide solution, but does give a slight precipitate of a light bluish 
color Avith copper sulphate solution. 
(7) To obtain a mixture giving the reactions noted above, about 2£ 
to 3 pounds of lime will be needed for each G pounds of copper sulphate 
used. 
(8) It is very much better to dilute both the copper sulphate solution 
and the milk of lime before mixing than to mix the strong solutions 
and dilute to the required quantity afterwards. 
(9) The mixture begins to deteriorate within a few hours after being 
made and should therefore be applied as soon as possible. It should 
never be allowed to stand as long as twenty-four hours before using. 
(10) The addition of soap to the finished mixture greatly increases its 
wetting properties and adds to its value for all plants with a Avaxy 
coating on the parts sprayed. The soap should be added in solution 
and in sufficient quantity to make the mixture foam Avell when stirred 
violently. 
(11) The very cheap resin soaps are sufficiently promising to deserve 
a thorough trial for use Avith the Bordeaux mixture. 
Subtropical Laboratory, 
Fustis y Fla. 
with about 2 parts of water when added to the Bordeaux mixture. This soap costs 
only about II cents a pound in large amounts, while whale-oil soap costs abont four 
times as much, and ordinary good hard soap costs five to twelve times as much. From 
a few preliminary trials made, it seems to be even better than ordinary soap to make 
a foam with Bordeaux. Albert Koebele found a similar resin soap to be a good insec¬ 
ticide for some baustorial insects (see Annual Reports of the Commissioner of Agri¬ 
culture for 1886 p. 558; 1887, p. 146; and 1888, p. 130). 
