120 president's address — SECTION B. 



ment to greater intellectuality known as the Renaissance period of 

 liistor)^, having been first introduced in the middle of the sixteenth 

 century in Saxony. Its object, however, was not directly connected 

 with copper-smelting. Its purpose was mainly the circumvention of 

 the use of an excessive amount of lead as a vehicle for the collection 

 of the precious metals in the blast-furnace treatment of ores. By 

 first concentrating them into a small bulk of iron matte, preferably 

 non-cupriferous, it cut off the source of very serious lead losses. De- 

 silverisation of this matte could be effected subsequently, with a smaller 

 quantity of lead, but copper, being an obstacle herein, was, if possible, 

 avoided. The departure was considered so happy and beneficial an 

 one at the time that Barthold Kohler, the inventor, it is recorded in 

 the archives of the day,(p) received the liberal gift of 2,000 florins 

 from the Elector, in recognition of this service to the princely treasury, 

 coupled with certain other improvements in metallurgical procedure, 

 which rendered lower grades of ore profitable. The operation consti- 

 tuted what is now known as raw-smelting (Roharbeit), or, as Dr. 

 Percy named it, " pyritic smelting." It continued to be extensively 

 practised in Europe, as a preliminary concentration method, until the 

 middle of the last century, when the advent of the method of roasting 

 the pyrites for our present sulphuric acid manufacture put an end to 

 it. It thus became almost a lost art, only surviving on a very limited 

 scale at Kongsberg, &c. But during its three centuries of currency, 

 as remarked, copper was as far as possible designedly eschewed in 

 connection with it. Neither was this entire time marked by any ap- 

 preciation whatsoever of the fuel-value of the raw pyrites used. As 

 a late instance we may mention Henkel, who, in the middle of the 

 eighteenth century, (q) published a most elaborate disquisitive work 

 on the value and importance of pyrites from all possible points of view — 

 mineralogical, chemical, metallurgical, and otherwise — but does not 

 betray the slightest notion of the " pyritic effect." This was only 

 possible after general chemistry had placed the knowledge of the true 

 nature of the atmosphere at the disposal of the arts. Yet, as above 

 stated, though the loss of sulphur was noticed and correctly explained 

 in the earlier days of this knowledge, the calorific usefulness of the 

 constituents of sulphide substances was not definitely discussed until 

 nearly a century after the discovery of oxygen (1774) and the recogni- 

 tion of the nature of sulphurous acid (1775). A single prominent 

 exception to this rule, in which a Bessemerising action in the blast 

 furnace was surmised to take place, is the case of the La Pise and 

 Pontgibaud treatment of pyritous lead ores. It was the practice there, 

 in the sixties, to add cast iron to the charge, and it was noticed that 

 an increase of this addition allowed a reduction of coke to be effected. 

 Thus, at La Pise, the increase of such iron from 2 per cent, or 3 per 

 cent, to 7 per cent., lowered the coke consumption from 25 per cent, to 

 22 per cent, and 20 per cent., while at Pontgibaud, when smelting 50 

 per cent, lead ore, the increase of the metal from 10 per cent, to 12 per 



(p) K. A. Winkler, " Freyberger Schmelz-hiittenprocesse," Freyberg, 1837. 

 (7) J. F. Henkel, " Pyritologia," Leipsic, 1754, 2nd ed. , transl. into English, 1757. 



