266 PETER SPENCE 



him to prosecute various researches, and from 

 this time forth the records of the Patent 

 Office reveal how varied were the subjects he 

 investigated, and how fertile he was in 

 resource. 



It is impossible for us in this short article 

 to follow his labours and ideas as they are 

 unfolded in his various patents ; we must 

 content ourselves with classifying his fifty-six 

 patents and summarising their results. 



The patent last described, and worked out 

 at the Pendleton Alum Works, was his main 

 achievement. On it he built up a very large 

 and successful business ; and the other 

 patents to which we shall advert are, for 

 the most part, quite subsidiary as compared 

 with it. 



The following are the subjects to which 

 his patents refer: 



1. Prussian Blue and Prussiate of Potash. 



2. Manufacture of Sulphate of Alumina 



and Alum. 



3. Manufacture of Copperas. 



4. Manufacture of Sulphuric Acid, and 



obtaining Sulphur from Iron Pyrites. 



5. Calcination of Copper and other ores. 



6. Separation of Copper from its ores. 



7. Separation of Zinc from its ores. 



