172 INTERNATIONAL CONGRESS OF VITICULTURE 



This wash was doubtless intended as a dormant spray, as it could not be 

 used upon foliage at this strength without very serious injury. The analysis 

 indicates about three-tenths of a pound of sulphur to each gallon of the spray. 

 Three gallons of Haywood's solution would therefore be equivalent to one 

 gallon of Volck's stock sulphide of potash solution. By using the correspond- 

 ing dilutions, the same results might be anticipated from either spray, both 

 having polysulphides and thiosulphate as the chief ingredients. 



COMMERCIAL PREPARATIONS OF THE ALKALI POLYSULPHIDES. 



Liver of Sulphur: This compound is not suitable for home preparation. 

 It is made commercially by fusing potassium carbonate and sulphur together 

 in a crucible. By the action of the heat, carbon dioxide is liberated and the 

 sulphur combines with the potassium. After the fusion is complete, the melt 

 is poured out on to iron plates where it solidifies into a mottled yellow and 

 chocolate colored cake. The sulphur is combined in the form of polysul- 

 phides and thiosulphates. Analysis of samples of liver of sulphur show total 

 sulphur to be between 40 and 50 per cent. 



Sulphides and Polysulphides: Both potassium and sodium have been 

 used as a base for the combination of sulphur in a form soluble in water. 

 Chemical examination of a number of brands shows a remarkable variation 

 in sulphur ' content, the range being from 17 to 42 per cent. In air cases, 

 however, the materials consisted mainly of alkali sulphides and thiosulphate. 

 Chemically, sodium is capable of uniting with more sulphur than is potassium, 

 on account of its smaller atomic weight. Except in the case of two proprie- 

 tary preparations, this fact has not been taken advantage of, for a sample 

 of liver of sulphur (potassium polysulphide) contained more sulphur than 

 any of the sodium compounds. An excess of uncombined sulphur was not 

 shown in any of the samples examined, except in the preparations sold under 

 a trade name. 



Proprietary Sodium Polysulphides: Quite recently there have been in- 

 troduced two commercial preparations of sodium polysulphides sold under 

 trade names. They also consist of a mixture of the polysulphides and thio- 

 sulphate but their sulphur content is greater than any of the other materials 

 examined of this character. Analysis indicates an excess of sulphur used in 

 their manufacture so that the maximum amount of sulphur may be rendered 

 soluble. The base being sodium, a greater amount of combined sulphur is 

 possible, and a cheaper product is produced than if the more expensive 

 potassium were used. They are both granular yellow powders readily 

 soluble in water and are advertised as a substitute for lime-sulphur solution. 

 The appearance of the diluted spray is identical in either case so that the 

 impression is quite general that these powders are a dry form of lime- 

 sulphur. The advertising matter of one of the preparations states that their 

 product is made by the fusion of soda-ash (impure sodium carbonate) and 

 sulphur by a patented process. 



The patent under which the other compound is made specifies "forming 

 a water-soluble material for spraying plants, by heating together about equal 

 weights of sulphur and caustic soda to cause reaction and drive off a portion 



