ISO ANDREAS KURTZ 



acid boiling, and is not acted on by magnet" 

 The quality of chrome ore appears to have 

 been decided more by its specific gravity than 

 anything else, as seen in the following 

 entries: 



Chromate of iron from Sweden, four sorts, sp. gr. 



24, 25, 27, 30. 

 Chromate of iron from East India, sp. gr. 23, like 



metal. 

 Chromate of iron from America, four sorts, sp. 



gr. 22 to 31. 



Best American, sp, gr. 22 quite metallic. 

 2nd best 23 fine black reddish colour. 

 3rd sort 23 dirty looking, ochre-like. 



Norway best 24 in square little tubes. 

 Shetland Island,, 32^- 

 From Cappe in 1831 sp. gr. 30. 

 American good, bad, altogether from mill, sp. gr. 27. 

 Norway, all mixed from the works, 27. 



Then there is a memoranda on the grinding 

 of chrome ore : " Our 4 stone in Parliament 

 Street do grind 800 Ibs. of fine ore per hour, 

 and our sifting machine can sift 1000 Ibs. per 

 hour. It was Scotch ore." 



The ore being ground, there are scores of 

 mixtures given, extending over several years, 

 from 1831 to 1838, of which we select a few 

 to illustrate his work : 



