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lY. 



A STUDY IN THERMO-CHEMISTRY : THE REDUCTION OF 

 METALS FROM THEIR ORES. Br W. N. HARTLEY, F.R.S., 

 Professor of Chemistry, Royal College of Science, Dublin. 



[Read December 17, 1890.] 



Notwithstanding the number of years during which Thermo- 

 chemistry has been investigated by Favre and Silbermann, 

 Andrews, Berthelot, and Julius Thomson/ there has been very 

 little application of the results attained to explaining the theory of 

 metallurgical processes. This communication contains a number 

 of thermo-chemical equations relating to practical details of the 

 kind. 



Explanation of the Terms used. 



When one substance A combines with another B, to form a 

 third substance C, there is a certain amount of energy lost or 

 gained. This is termed heat disturbance, since energy can be 

 measured in terms of heat. The change above may be put in the 

 form of an equation — 



A + B = C ± q heat-units. 



Here it must be understood that when A and B combine, as, for 

 instance, when carbon combines with oxygen, they do not form 

 AB, like + = CO, because the energy associated with A and 

 B is not the exact quantity associated with the third substance. 

 This latter C differs hy ± q heat-units from A + B. 



A gramme atom is an atomic weight in grammes. 



A heat-unit is the quantity of heat required to raise 1 kilo- 

 gramme of water 1^0. 



1 For information on this subject, see '* Ostwald's Chemistry," translated by 

 Dr. Walker; " Thermo-Chemistry," by Pattison Muir; " Chimie Elementaire," par 

 A. Ditte; also Richter's " Chemistry." 



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