46 



oxidising, and forming polysulphides of calcium, thiosulphate 

 and hydrosulphate of calcium. The waste is then lixiviated, and 

 the liquid removed, the residue being again treated as above several 

 times. 



No. 3. Sulphur liquor, the soluble portion of oxidised alkali, 

 or tank waste. 



The oxidised waste, lixiviated in the vats with warm water, 

 gives a yellow solution containing polysulphides of calcium, 

 thiosulphate of calcium, and hydrosulphate of calcium. 



Liquor generally contains equal to 5*0 of sulphur, distributed 

 as follows : 



2'0 calcium thiosulphate. 

 2 - polysulphide of calcium. 

 TO hydrosulphate of calcium. 



No. 4. Precipitated sulphur, formed when sulphur liquor and 

 hydrochloric acid are mixed. 



Sulphur liquor is mixed with common hydrochloric acid from 

 the condensers, the mixed liquors being heated to 140 Fahren- 

 heit, and well stirred. 



The hydrochloric acid forming chloride of calcium in the liquor, 

 sulphur is deposited as a yellow flocculent precipitate. 



In a good sample of liquor all the sulphide of hydrogen 

 disengaged by decomposition of the sulphides reacts on the 

 sulphurous acid liberated at the same time from the thiosulphate, 

 sulphur and water being the products. 



No. 5. Lump sulphur, prepared by melting the moist sulphur 

 of a previous stage of the process in a strong cast-iron vessel. 



After washing out the chloride of calcium from the moist 

 sulphur, the drained product is put into a strong cast-iron 

 cylinder, the filling -in aperture screwed down, and steam of a 

 pressure of 35 Ibs. admitted through a coil of cast-iron pipe. 

 The sulphur rapidly melts, and at the expiration of a certain 

 time, found out by experience, the whole charge is forced by the 

 pressure of the steam through the discharge pipe into tight 

 wooden waggons, and when cool broken up for sale. 



No. 5a. Roll sulphur. The roll brimstone of commerce used 

 in medicine. Melted sulphur run into round wooden moulds and 

 allowed to cool. 



154. Illustrations of the manufacture of chlorate of 

 potash. 



1876. Exhibited by James Muspratt Sons. 



No. 1. Muriate of potash containing about 90 per cent, 

 potassium chloride, and some impurities consisting of sodium 

 chloride, sulphates of potash, soda, lime, and magnesia. 



No. 2. Milk of lime of about 1'08 specific gravity, made by 

 well stirring up about 18 ctr. slacked lime in about 6,800 litres 

 water in a cast-iron vessel. The sample contains a small 



