, 1911-02-11

blade placed therein and allowed to remain
for a few minutes, OF even for several hours.
If the polished surface shows any reddish
deposits OF copper, more lime must be added;
bat if it comes out bright, the mixture is
safe to use. With the ferrocyanide test, it
is only necessary to add a drop to a small
amount of tire mixture if any reddishbrowp
colour is seen, it requires more lime.
Stock solutions of known strengths might
be kept made up, 50 that to prepare Bor-
deaux mixture it would be ne. essary merely
to pour together a certain amount Of the
lime stock and the sulphur stock, and
add the correct amount Of water. If
the stock solutions contained l Ii. OF
lime or of copper sulphate in each gallon,
the calculations necessary IN preparing q
mixture of Bordeaux according to any ordi-
nary formula would be a simple matter. For
example, to prepare 20 gallons of Bordeaux
according to the 4-4-5O formula, only 2 gal
Ions of copper s~ulphate stock, 2 gallons of
lime stock and II gallons Of water would be
necessary.
Care would have to be exercised that the
strength Of the stocks was kept constant, as
evaporation Of the water would tend to CON
centrate the stock preparation.
Professor Pickering has published in the
Transactions Of the Chemical iS0cietY 18),
interesting results of experiments III the
making and use of Bordeaux mixture, and
an account Of this work has been given in
the summary Of the Eighth Report of the
Woburn Experimental Fruit Farm.
The author concludes that excess of lime
impairs the efficiency of Bordeaux mixture,
and that the old formulas for making it
were based on wrong principles, He su9-
gests the use of 6 th. 81 OF. Of copper sui
,Ioto l;,ccIvoJ ~ , ar z ,roIIloo r. W. ~.
and 2 or 3 III. of fresh lime to make 100 gall
Ions of Bordeaux mixture. The copper sui
phate is dissolved and the lime slaked md
stirred mp in about 100 gallons of
water. When the lime has settled, SO gal
Ions of the clear lime water is drawn off and
mixed with the copper sulphate solution,
and the whole made up to 100 gallons. Soft
water should always be used, aud the mix
ture tested by the knife blade test or the
ferrA cyanide Of potassium test, and if the
copper has not all been precipitated, more
lime water should be added.
Made according to this method, 100 gal
Ions of the mixture requires the use of small
er quantities of copper sulphate and lime,
than when made according to the old method,
and it is said toll equally efficient and no
more liable to iniure the foliage of plants.
Trials in Hawaii Q9) however indicate
blhb " t1COklLCAI - NULC ups OI0 IlhIOSp
Pickering's Bordeaux mixture is not suit
able, and it would seem that further expert
mental trials were necessary before it could
be concluded that the old method of making
Bordeaux mixture can be replaced entirely
by the new one.
Directions For Using Bordeaux Mixture,
Cane pla ats and similar plant material to
be treated should be immersed in Bordeaux
mixture, which should thoroughly wet the
surface of the plants, the object being to coat
thom with q film Of the copper solution. A
wooden crate, or a basket made of galva-
nized mesh wire, will be found convenient
for holding the canes, during immersion i'll
the trough or tank Of the mixture.
1t would be possible to agitate the mixture
and cause it to flow over and between the
plants by lifting the baskets gently two or
three times, and this would not iujure the
buds so much as stirring the cuttings when
they are thrown into the trough en- nsusse.
= West Itdton Bulletin, Vol. X No. 4.