55 



oxalic acid is isolated by precipitation as oxalate of lime, and 

 the subsequent decomposition of this latter product by sulphuric 

 acid. Specimen No. 2 is crystallised from water. A comparison 

 will show the marked difference in crystalline form due to the 

 presence of sulphuric acid. 



180. Binoxalate of potash. 



1876. Exhibited by Roberts, Dale, $ Co. 



181. Spence's process for -the manufacture of alum. 

 Specimens to illustrate the process. 



1876. Exhibited by Peter Spence If Sons. 



(1.) Shale of the coal measures before calcination (source of 

 alumina). 



(la.) Shale after calcination. 



(2.) Two samples of pyrites or bi-sulphide of iron (source of 

 sulphur for the manufacture of sulphuric acid). 



(2a.) Nitrate of soda, for oxidising the sulphur dioxide pro- 

 duced from the pyrites into sulphuric acid. 



(26.) Sulphuric acid, specific gravity 1*6, as used in the manu- 

 facture of alum. 



(3.) Gas liquor (source of ammonia). 



(3a.) Sulphate of ammonia (2 specimens). 



(4.) Sulphate of alumina. 



(5.) First crystals of ammonia alum (a double salt or compound 

 of sulphate of ammonia and sulphate of alumina). 



(0.) Ammonia alum. Second crystallisation. 



(7.) Large group of alum crystals. 



182. Alum octahedra showing typical form of alum 

 crystals (2). 



E. 191c. and e. 1888. Given by Peter Spence Sons. 



183. Chemicals for use in various manufactures. 

 1876. Exhibited by W. J. Norris If Brother. 

 Liquid archill, made from Orchella weed, for dyers and 



printers. 



Sulphate of alumina, for sugar refiners, paper makers, and 

 dyers. 



Aluminous cake, for paper makers. 



Cudbear, made from Orchella weed, for dyers. 



Bichromate of potash, with samples of chrome ore, limestone, 

 and sulphate of potash, from which it is made. 



184. Samples of dye-stuffs. 



1876. Exhibited by J. Marshall, Son fy Go. 



Orchella weed Ceylon. 

 Orchella weed, California. 



Cudbear, red shade. 

 Cudbear, violet shade. 



