﻿DRY SUBSTITUTES FOR LIQUID LIME-SULPHUR 7 



is first to prepare commercial lime-sulphm' solution in the usual 

 manner, then to add a "stabilizing" substance (usually cane sugar), 

 and finally to evaporate the solution to dryness, either in vacuo or at 

 atmospheric pressure in the presence of an inert gas. Several patents 

 have been issued for the preparation of a dry lime-sulphur,^ but 

 practically all of that produced at the present time is made by the 

 process of evaporation under reduced pressure in the presence of 

 a ''stabilizer." 



CHEMICAL COMPOSITION 



Commercial drj^ calcium-sulphur, or dry lime-sulphur as it is usually 

 called, contains a relatively large percentage of insoluble matter, con- 

 sisting cliiefly of free sulphiu- and smaller amounts of calcium sulphite 

 and lime. This liigh percentage of insoluble matter is objectionable 

 because it decreases the active ingredients and tends to clog the nozzle 

 of the spraying apparatus. The average composition of six different 

 brands of dry lmie-sulphurs,^° representing the principal brands on 

 the market, are .given in Table 1. 



Table 1. — -The chemical composition of representative dry lime-sulphurs 





Average percentage found 















Number 



Brand 



Calcium 

 polysul- 

 phides 1 



Calcium 

 thiosul- 

 phate 2 



Free 

 sulphur 



Other 

 ingre- 

 dients 

 (diff.) 3 



of samples 

 averaged 



A 



67.31 



6.96 



8.44 



17.29 



10 



B 



64.67 



9.66 



10.31 



15.36 



10 



C 



70.59 



8.72 



8.09 



12.60 



4 



D 



59.68 



8.15 



11.79 



20.38 



5 



E - 



60.82 



6.42 



14.08 



18.68 



4 



F 



64.69 



9.09 



8.87 



17.35 



10 



Weighted average - 



64.90 



8.34 



9.86 



16.91 



43 



' The sum of the polysulphide sulphur and the polysulphide calcium. 

 2 Thiosulphate sulphur calculated to calcium thiosuiphate, CaS203. 

 2 Mainly water, sugars, calcium sulphite and insoluble impurities. 



EXPERIMENTS IN 1921 



For the experiments made in Indiana in 1921 an old apple orchard 

 at Washington, Ind., badly infested with the San Jose scale, was used. 

 This was divided into plats of three to five trees, each with approx- 

 imately the same infestation. A dormant spray was applied on 

 March 22 and 23, using a power sprayer maintaining a pressure of 

 225 pounds, with two spray guns. From 9 to 12 gallons of spray 

 were applied to each tree. 



The composition and dilutions of the essential materials used are 

 given in Taole 2. 



• United states patents Nos. 460,227; 997,601; 1,186,564; 1,231,741; 1,254,908; 1,336,967; 1,338,678; 1,374,961; 

 1,422,977; and l.iZi.mr,. 

 "' .Material piirohascl on the open market. 



