D. CHEMISTRY AND METALLURGY. 211 



oxide of iron, which is itself consumed in the puddling and 

 blast furnaces. In view of these facts, Professor Hunt hopes 

 to see a similar use made of the great deposits of pyrite, 

 rich in sulphur and often in copper, which abound in the 

 Blue Ridge in Virginia, North Carolina, and Tennessee. Large 

 quantities of these ores are now being treated for the manu- 

 facture of copper at Ducktown, Tennessee, and at Ore Knob, 

 North Carolina; and many other points in this region, in the 

 opinion of Professor Hunt, are destined to become the seats 

 of an important copper industry. It therefore becomes a 

 question how those ores which are richest in sulphur may 

 be most advantageously brought into contact with the abun- 

 dant phosphates of the South Carolina seaboard. The ex- 

 traction of copper as a secondary product from these ores 

 will enable us to make acid cheaply, and to supply cheap fer- 

 tilizers to the cotton-fields of the South. The fear having 

 been expressed that these ores might contain notable quan- 

 tities of arsenical compounds, Professor Hunt asserts them 

 to be quite as free from this impurity as the Spanish ores so 

 largely utilized in England. Upon this point, he furthermore 

 remarks, the exceeding rarity of arsenical compounds in this 

 region was long ago pointed out as a significant fact by 

 Professor Henry Wurtz, of New York, in a paper " On the 

 Cobalt and Nickel Ores of North and South Carolina," in the 

 American Journal of Science for 1859 ; and this is confirmed 

 by the experience of those who have been familiar with the 

 metallurgical treatment of the pyritous ores of Ducktown 

 and of Ore Knob, already mentioned. 



NEW VIEWS OF CHEMICAL AFFINITY. 



Dr. E. J. Mills has made an interesting application of prin- 

 ciples first evolved by Esson to some observations made by 

 Dr. Gladstone, and published in 1855 in his work entitled " Cir- 

 cumstances Modifying the Action of Chemical Affinity." Mr. 

 Esson had in fact shown that when a substance undergoes 

 chemical change, the process takes place at a rate that has a 

 relation to the mass of the substances acting upon each other 

 at any given moment during the process, and the relation 

 between the time and the quantity of the chemical still un- 

 changed at any moment may be expressed either by a com- 

 plex analytical formula or by a logarithmic curve. This 



