4 BULLETIN 451, U. S. DEPARTMENT OF AGRICULTURE. 
sulphid in cold dilute solution. Despite the intimate contact of the 
materials for 10 days and the high plus reaction figure at the end, the 
analytical figures for the various forms of sulphur were only slightly 
affected, and the value of x in CaS x was reduced from 4.81 in sample 
G-2 only to 4.45 in sample G-3. Therefore for horticultural spray- 
ing purposes it appears that lime may be added to the diluted solu- 
tions shortly before use without seriously affecting the various sul- 
phur compounds. 
After completion of the preliminary experiments on the effect of 
storage, the main investigation could be undertaken on the effect- 
produced by varying formulas and conditions. 
EFFECT OF VARYING LIME-SULPHUR RATIO. 
EXPERIMENT 3. 
Here lime was the only variable, the amount of sulphur and water and the 
period of boiling being maintained constant. The concentrated solutions were 
prepared as described under experiment 1, and. in fact, the majority of them 
were the same samples, as shown by the identification letters. All determina- 
tions were made on freshly prepared dilutions of concentrates which had been 
stored not less than two months after decantation from sediment, except in 
case of sample G, stored for 33 days. The results are given in Table 2. 
"With increasing proportion of lime the percentage of thiosulphate 
sulphur increases throughout, but the parallelly increasing percentage 
of monosulphur. together with other analytical values, drops after 
passing Preparation D merely on account of deposition of poly- 
sulphid in crystalline form, as is well known to occur sometimes in 
preparations made with an excess of lime. Polysulphur reached its 
maximum value at the lime-sulphur ratio 0.45 in Preparation B. as 
did also total sulphid sulphur, although total sulphur continued to 
make a very slight further gain. But probably the most illuminat- 
ing results are shown by the analytical ratio of total lime to total 
sulphur. Equal utilization of lime and sulphur begins with Prepara- 
tion B. where the analytical ratio 0.450 comes out exactly the same as 
the formula ratio. An excess of sulphur over that ratio, as in Prepara- 
tion A. produced no higher polysulphid and simply was not utilized. 
With increasing lime-sulphur ratio equal utilization of lime and 
sulphur continues certainly into the close vicinity of the ratio 0.500. 
though at that point results begin to be obscured by the deposition of 
crystals. But increased ratio means a lower polysulphid, as is clearly 
shown. 
For each molecule of thiosulphate formed in the reaction there 
was produced an average of about 1.84 molecules of polysulphid. 
The individual variations from the average seem in no way to be 
consistently dependent upon variations in formula. This ratio will 
be discussed later. 
