454 Mr. J. Napier on Copper Smeltivff. 



into the condition of sulphurets in smelting, they are seldom 

 mixed with the sulphuret ores, but with the calcined coarse 

 metal from these ores to be described. 



]\I. F. Le Play, in his Precedes Metallurgiques, has divided 

 the ores into seven classes, and pointed out their distribution 

 in the operations in the works as follows : — 



1st. Ores containing from 3 to 15 per cent, of copper, mostly 



pyrites, with sulphuret of iron, and much earthy and other 



impurities. 

 2nd. Ores of the same character as the first, but richer, having 



from 15 to 25 per cent, of copper. 

 3rd. Ores requiring no calcination, having little sulphur and 



much oxide of copper, the per-centage of copper being between 



12 and 20. , 

 4th. Ores composed of oxides and carbonates of copper, subsul- 



phm'cts with small portions of pyrites, the matrix being oxide 



of iron and quartz. 

 5th. Same as the first class, but known to have no deleterious 



matters in them, such as tin, antimony, &c. 

 6th. Ores, principally subsulphm-ets, having a per-centage of 



from 60 to 80 of copper. 

 7th. The waste matters collected about the works termed, as we 



have already noticed, cobbing. 



As this author describes ten operations as necessary in the 

 manufacture of copper, his observations and descriptions must 

 have reference to a period previous to the introduction of so 

 much rich foreign ore, and some of these descriptions are there- 

 fore not applicable to the present time, the general routine of 

 operations being now only six. The want of a definite rule to 

 guide the smelter in mixinghis ores is a desideratum we think easily 

 supplied by investigation and attention. In the last section we 

 mentioned that silica, alumina, &c. were by themselves infusible, 

 but at high temperatures readily combine with other matters 

 and form compounds that are easily fused ; and in these com- 

 binations there are kinds and quantities of these substances much 

 more easily fused than others. The first object of the smelter 

 being to separate the metallic portion of the ore from the earths 

 with the least expense and trouble, the having a mixture that will 

 give him an easily flowing scoria, is a primary consideration. 

 This, no doubt, could be easily obtained iu the same way as 

 shown in assaying, by adding flux ; but every addition of flux is 

 a loss in the smelting of copper, and should always be avoided 

 if possible. In all combinations, to cff'ect perfect fusion 

 reitain proportions are necessary to form a fusible compound, in 

 the same way as in ordinary combinations. For example, to dis- 



