THE NATIONAL NURSERYMAN 
509 
the magnesium, iron, aluminum and other insoluble impurities in 
the lime and sulphur used. Its volume is affected chiefly by: the 
ratio of lime and sulphur; the purity of materials; and the time of 
boiling. Its relative volume also naturally increases with the 
density of the product. Made as described above its actual volume 
apparently runs from 5 % to 9 % of the total product. 
In the home preparation, the difficulty of its economic removal 
and its fineness and apparent lack of objectionable mechanical quali¬ 
ties, except in displacing valuable materials, have led us to disregard 
it. If desired, however, it may be removed by letting the product 
settle for about a day, drawing off the clear portion and straining the 
remainder through a moderately fine cloth inside the strainer. The 
sludge may then be washed free of any further valuable materials in 
the manner stated above. 
THE PRESERVATION OF LIME-SULPHUR 
If properly handled, lime-sulphur preparations apparently can 
be preserved indefinitely. Ordinary changes in temperature have 
little effect on them. But they are very sensitive to a number of 
other influences. Continued exposure to air, for example, results 
in the development of a crust of solids of varying thickness. This 
is prevented by cutting off the exposure to air, either by an oil 
covering or by immediate storage in tight closed vessels, filling them 
completely. When the crust does develop it can be skimmed off 
with a fine screen and readily redissolved by heating either in water 
or in the concentrate itself. 
These solutions are also decomposed by a number of other things. 
Acids, carbon dioxid, certain arsenicals, and even extra lime put in 
as a marker, all appear more or less rapidly to break down the lime- 
sulphur combination. This is by no means always fatal in practical 
results, but we believe it is to be avoided when possible. Most of 
them can be avoided by elimination. 
In the case of arsenicals, however, their addition is necessary, if 
the material is to be used as a summer fungicide. The addition of 
aresnate of lead results in very rapid decomposition, both of itself 
and the lime-sulphur. The resulting compounds seem to give good 
results practically, however, so that we cannot entirely condemn the 
process just at present. But it seems to be a very wasteful process, 
especially when we can obtain the same poisoning power in another 
arsenical, the arsenite of lime, for about one-sixth the cost. The 
latter arsenical also is practically stable in the lime-sulphur solution. 
It has been in use to a greater or less extent for a long time in connec¬ 
tion with other fungicides, but has been limited by a tendency to 
burn foliage. This is practically avoided by making it up with a 
slight modification of the Kedzie formula, the method being described 
in the above mentioned bulletin of the Pennsylvania Station. The 
use of Paris green in this solution, we believe to be undesirable, with 
nothing to commend it. 
THE PROCESS OF DILUTION 
In the application of any concentrate, either home-made or 
commercial, it is essential that a definite method of dilution be 
followed. Two solutions may look exactly alike and yet differ 
widely in density, so that any accurate method must be based pri¬ 
marily on the density of the concentrate that is being diluted. 
Moreover, we believe that recommendations based on the density of 
diluted spray are preferable to those based on the number of dilu¬ 
tions even when accompanied by a statement of the concentrate’s 
density. 
Accurate dilution is very simple and easily accomplished with 
the aid of a hydrometer having the specific gravity scale 1 . Sprays 
of any desired density may be obtained from any concentrate by 
simply getting the reading of the concentrate and dividing the 
decimal of this reading by the decimal of the spray desired. For 
example, if the reading of the concentrate is 1.27 (about 31 Baume), 
to get a spray of 1.03 density we divide the .27 by .03 and obtain 
nine, which is the number of dilutions required, and which of course 
is obtained by adding eight volumes of water. In this we are simply 
applying the general fact that the densities of solutions heavier than 
water vary inversely with the number of dilutions. 
The workings of the process may be seen further in the following: 
(a) To determine number of dilutions. 
Decimal of concentrate 
Formula: —— ; --— -—— ; —- = No. of dilutions 
Decimal oi Sprsy Desired 
Times and Strengths of Spray for Various Purposes 
Insect or Disease 
Spraying Times 
San Jose Scale, 
Oyster-shell Scale, 
Trees dormant, but best in fall or spring. 
At hatching time. 
1.03 for regular annual control. 
1.04 in bad cases, especially on old 
apple trees, 
1.02, 
Blister-mite, 
Plant lice, 
Peach leaf curl, 
Just before buds open. 
103. 
Apple and pear scab, 
Apple worm, add arsenical in 2 and 3 
(1) Blossoms beginning to show pink. 
(2) Within a week after petals fall, 
(3) About three weeks later. 
1.01, may be varied by .002 or more 
either way as results direct. 
Cherry leaf spot, 
Three sprayings, a month apart, begin¬ 
ning with signs of infection. 
1.01, or slightly weaker. 
Peach scab and brown rot of stone 
fruits 
(Experimental as yet.) 
(1) Three or four weeks after petals fall, 
(2) Half-way between (1) and (3). 
(3) Two weeks before fruit ripens. 
1.003 t° 1-005, may be varied .001 either 
way, as results direct. 
On peaches and plums, limited trials 
only, testing effect on foliage by apply¬ 
ing to a few trees several days before 
regular applications. 
1 The presence of foreign soluble materials or of much roily sediment in the 1 Such an instrument, fitted with the Baume scale also, may be obtained from 
sample will vitiate the test, a fact which must be taken into consideration the Bausch & Lomb, Rochester, N. i., or from the firms mentioned in our Bulletin 92. 
former especially in solutions of unknown preparation.” 
