642 SEC. 13. CHEMISTRY. 



Boiler. By the corrugated form of bottom (Prentice's patent) the greatest 

 possible amount of strength, surface, and consequent evaporating power is 

 obtained, and a considerable saving in fuel is effected. 



Pans. By means of these vessels the large and costly leaden tanks for the 

 previous concentration of the chamber acid, which require constant repair and 

 renewal and more or less contaminate the acid, are entirely done away 

 with. 



The setting of these boilers and open pans is of the simplest kind ; they are 

 placed upon an iron frame over a straight flue, and they may be multiplied or 

 enlarged to any desired capacity of production, without sacrifice of existing 

 plant. 



Cooler. An improved economical and convenient form, securing great 

 cooling power with a minimum of water and space. 



The total cost of such apparatus composed entirely of platinum, and, there- 

 fore, alvraj's of great intrinsic value in comparison with the first outlay, is less 

 than that of any other form yet introduced. 



Briefly, the chief advantages of this construction are : 



Great economy in first outlay and daily expense of working. 



Great intrinsic value in a realisable form in proportion to the cost. 



Purity of acid, and freedom from danger. 



2689. Common Salt. From the salt works of North wich, 

 Cheshire, used in the manufacture of salt cake or sulphate of soda. 



Sullivan fy Co. 



2690. Salt Cake, or commercial sulphate of soda, containing 

 about 98 per cent, of real sulphate, made by decomposing common 

 salt with vitriol in an iron pan heated externally. When about 

 three fourths of the decomposition has been effected, the charge is 

 pushed upon the bed of a " muffle" furnace, maintained at a bright 

 red heat till the decomposition is completed. The gaseous hydro- 

 chloric acid evolved during the process is conducted away through 

 pipes or flues to condensing towers, where, being absorbed by 

 water, it assumes the form of liquid acid. Sullivan Co. 



2691. Limestone, or native carbonate of lime from Derbyshire, 

 used in combination with slack or small coal for converting salt 

 cake or sulphate of soda into carbonate of soda. Sullivan Co. 



2692. Slack, or small coal from the Lancashire coalfield, used in 

 combination with limestone for converting salt cake or sulphate of 

 soda into carbonate of soda. Sullivan $ Co. 



2693. Black Ash, or ball soda, containing about 24 per cent, of 

 soda, produced by fluxing together in a suitable furnace a mixture 

 of salt cake or sulphate of soda, limestone, and slack, by which 

 means the sulphate of soda is converted into carbonate of soda, 

 the carbonate of lime of the limestone into calcium sulphide, and 

 the slack into coke. Sullivan fy Co 



