772 The Wohum Experiments on “ Potato Disease.” 
Plan of Experiment. — It is desirable here to note the points of 
difference between the present experiments and those conducted by 
the Society in other parts of the country. In the first place, the 
dressings employed comprised not only the ordinary houillie borde- 
laise, made up of sulphate of copper, freshly-burnt lime, and water, 
but also the kind known as houillie bordelaise suer^e, which contains 
molasses in addition to the other ingredients. This was tried, inas- 
much as some laboratory experiments made in France by M. Girard 
pointed to the mixture containing sugar as being more eflicacious than 
the ordinary houillie, the syrup probably helping to retain the copper 
salt more firmly on the leaves and thus rendering it less likely to be 
removed by heavy rain. The ordinary houillie used was made up with 
double the quantity of lime used in the Society’s other experiments, 
this composition being, however, one of those freely recommended 
in France ; it had the advantage, too, of making the comparison 
between the inclusion and the omission of molasses more definite. 
The dressings employed were, accordingly : — 
Mixture I. Bouillie Bordelaise. 
20 lb. sulphate of copper, 
20 „ lime (unslaked). 
100 gallons water. 
Mixture II. Bouillie Bordelaise Sucrie. 
20 lb. sulphate of copper. 
20 „ lime (unslaked). 
20 „ molasses. 
100 gallons water. 
In addition, trials were made of two other methods of treatment 
which have been advocated. The first was, to steep the “ seed ” 
potatoes in a solution of sulphate of copper before planting them, 
as is often done in the case of seed-wheat. The second was, to 
steep the seed-potatoes for twenty-four hours in a solution made up 
as follows : — 
6 lb. sulphate of ammonia. 
6 lb. nitrate of potash. 
25 gallons water. 
A few small plots were devoted to these two last-named experi- 
ments. 
The general experiment with the houillie bordelaise treatment 
was divided into two parts : — 
{a) A main experiment on three selected varieties of potato. 
\h) An experiment on a smaller scale with varieties specially 
susceptible to disease. 
(a) The Main Experiment. — Three well-known varieties of 
potato, representing respectively an early, a medium, and a late 
crop, were chosen. These were “ Beauty of Hebron ” (early), 
“Scotch Regents” (medium), and “Champions” (late). Three 
plots, each one-quarter acre in size, were devoted to each variety, as 
follows : — 
