151. Bicarbonate of soda (lump), prepared by exposing 

 crystals of carbonate of soda to a current of carbon 

 dioxide till saturated, and drying the product. 



1876. Exhibited by John Hutchinson fy Go. 



The dry lump bicarbonate ground in a mill and dressed to 

 separate coarse particles, as in grinding and preparing flour from 

 wheat. 



152. Bicarbonate of soda. Carbonate of soda of the 

 shops,used in medicine and for making effervescing drinks. 



1876. Exhibited by John Hutchinson fy Co. 



Soda crystals, or carbonate of soda, made by dissolving the 

 soda ash of Leblanc's process in hot water, and, after settling, 

 allowing to cool and crystallise, are put in an air-tight iron 

 chamber, and carbon dioxide (prepared by decomposing lime- 

 stone with waste hydrochloric acid from the condensers) turned in 

 by a pipe on the roof of the chamber. After some hours the 

 crystals are changed into bicarbonate of soda, part of the water 

 of crystallisation escaping during the process. 



The moist bicarbonate is dried in kilns heated not over 100 

 Fahrenheit. 



153. Chemicals illustrating the recovery of sulphur 

 from alkali waste. 



1876. Exhibited by John Hutchinson fy Go. 



No. 1. Soda waste, alkali waste, black ash waste, or tank 

 waste. Insoluble residue formed in the second or black stage of 

 Leblanc's process for obtaining soda from common salt. 



From the appended analysis by Kopp of a sample it will be 

 seen that a large quantity of sulphur is present in the waste. A 

 part of this can be profitably extracted by Mond's and other 

 processes. 



Sodium sulphide - 2,880 



Carbonate of lime - -13,636 



Silicate of lime - 5,680 



Hydrate of lime - 8,588 



Monosulphide of calcium - 22,162 



Alumina, magnesia - - 1,466 



Sulphide of iron - 2,670 



Carbon - - 1,800 



Sand - 2,000 



Water - 36,700 



Combined water and loss - - 2,418 



No. 2. Oxidised soda, alkali, or vat waste. 



In Mond's process a current of air at the ordinary temperature 

 is forced through the waste as it lies in the vats, directly the 

 last soda liquors are drained away. The waste becomes hot, 



U 64846. D 



