NATURE AND SOURCE OF SPRAYING MATERIALS. 191 



forms i.s usually suthciently high for the use of the horticulturist. 

 Brimstone and tlour of sulphur are usually about 98 per cent pure, 

 while flowers of sulphur is almost entirely pure. Brimstone weighs 

 most, flour of sulphur less, and flowers of sulphur least for a like 

 bulk. 



The horticulturist uses sulphur in all the above-named forms, brim- 

 stone being employed for bleaching fruit, nuts, etc., while flour and 

 flowers of sulphur arc used in held work for the control of insect and 

 fungous pests. A simple mode by which one may test the purity of 

 sulphur is to weigh out any desired amount and then dr}^ and l)urn 

 it; the weight of the remaining incombustible portion, added to the 

 amount of weight lost in drying, determines the amount of impurities. 



The sources of the sulphur supply of the United States are numer- 

 ous and varied. A large amount of crude sulphur is imported, 

 although nmch of the sulphur now used in the production of copper 

 sulphate, sulphuric acid, and various other chemicals is obtained in 

 the United States through the decomposition of s(>V(n-al native metallic 

 sulphides, such as the sulphides of iron and copper, which are known 

 as iron and copper pyrites. It has been estimated that the amount of 

 sulphur consumed in the United States in 1892 was 248,154 tons. The 

 sources of this sulphur were as follows: 



From 100,721 tons of imported brimstone (98 per cent) 98,707 tons. 



From 1,825 tons of domestic brimstone (98 per cent) 1,787 tons. 



From 210,000 tonn of imported pyrites (43 per cent) 90,300 tons. 



From 119,000 ton.s of domestic pyrites (44 per cent) 52,360 tons. 



At the present time the amount used is probably much greater than in 

 18112. 



Great deposits of native sulphur are found in many foreign coun- 

 tries and in various portions of the United States. Most of the 

 natural deposits occur in past or present mountain regions, and are 

 of volcanic origin. "The exhalations of volcanoes include, as a rule, 

 sulphurous acid (SO.,) and sulphureted hydrogen (H^S), which two 

 gases, if -moist, readily decompose each other into water and sulphur, 

 a circumstance which accounts for the constant occurrence of sulphur 

 in all volcanic districts.^' It is estimated that 5,000,000 tons of sulphur 

 exist in one deposit in Japan. The deposits of Sicily are famed the 

 world over, and 400 distinct workings are said to exist in that island. 

 In central Sicily, at Assoro, Imera, Villa^rosa, and elsewhere, large 

 amounts of brimstone, in the form of short truncated pyramids, are 

 commonly seen piled near the railroad stations, as wood is piled in the 

 United States. These large blocks, probably weighing 100 pounds each, 

 are brought to the railroad on the backs of donkeys driven down from 

 the mines in the mountains in long trains. Large refineries, devoted 

 to the refining of such brimstone, are located at Catania. The annual 

 output of sulphur in Sicily is said to exceed 300,000 tons, and the present 



