71 
Geni;ral Results of the foregoing eleven Experiments. 
An examination of the column of the preceding table showing- 
percentages of "September benefit" for the various kinds of treat- 
ment enables us to divide at once the series of experiments into four 
groups — three of three experiments each, and one of two. The first 
six experiments were all made in the same orchard, and all in March. 
It is especially interesting to see that the first three, in which the in- 
secticide was a simple lime and sulphur solution without salt or blue 
vitriol, show ratios of 74 to 79 per cent, of benefit, with an average 
of 76.3, while the next three experiments, all made with the "Cali- 
fornia wash," the composition being the same as that of the preced- 
ing three except that salt was added, give ratios of benefit ranging 
from 64 to 68 per cent., with an average of 65. 
These experiments strongly indicate, if they do not substantially 
prove, that the addition of salt to the lime and sulphur is a detriment 
rather than a benefit, since a difference of 17 per cent., or more 
than one sixth, in the ratios of apparent benefit, under conditions 
otherwise so uniform, can scarcely be accounted for in any other 
way. 
The next group of experiments, 7 to 9 of our series, when con- 
trasted with Experiments 4 to 6, show a difference in final effect of 
spring and midwinter sprayings. The average benefit of the "Cal- 
ifornia wash" applied to 187 trees in March was 65 per cent., while 
that of the Oregon and California washes applied to 320 trees i.i 
January was 46 per cent. — a difference of 41 per cent, in favor of 
the spring treatment. The January group of three experiments does 
not compare exactly with the March group of three, since two of 
the former were made on a different orchard from the latter, and 
were made with the "Oregon wash" instead of the "California 
wash." If, however. Experiment 8 be compared with Experiment 6, 
in which all the conditions were identical except the time of spray- 
ing, we get the same difference of ratios of benefit as before — 45 per 
cent, for the January treatment and 64 per cent, for the ^ I arch 
treatment. 
Furthermore, the "last two experiments, 10 and 11 of our series, 
contrast still more strongly with the three preceding, giving but 19 
and 23 per cents of benefit, with an average of 21 per cent, as com- 
pared with 46 per cent, for the preceding group. This difference 
of more than 100 per cent, can be accounted for only on the suppo- 
sition that the cold solution of lime and sulphur made with soda 
was far less efficient as an insecticide than the ordinary form of 
Oregon and California washes made by boiling. 
