THE president's ADDRESS. 259 



the Cornish, ores contain more silver than the Spanish, yet they 

 vary so very much in their composition that no two parcels are 

 alike : therefore, there arises the great inconvenience of being 

 obliged entirely to change the process with each lot, in order to 

 treat them successfully. We hope, however, this inconvenience 

 may be overcome, and Cornish ingenuity will surely be equal to 

 the task. 



Bearing then in mind that the Cornish pyrites is known to 

 contain more silver than the Spanish ores, and nearly as much 

 of the other metals ; let us look at the result of the operations 

 at the Widnes Metal Works. There about 22,000 tons of 

 Spanish burnt ores were worked by M. F. Claudet's wet process 

 during 1875. The auriferous silver extracted, sold for £2,600, 

 which is equal to 2s. 3Jd. per ton, and after every expense of 

 treatment (coals, labour, loss of iodine, wear and tear), a profit 

 was left of £2,100 or Is. 10 Jd. on each ton of burnt ore operated 

 upon. Although the proportion of silver recoverable from each 

 ton of Spanish burnt ore appears small, yet if the whole amount 

 of 365,000 tons and upwards were treated in a similar manner 

 by Claudet's process, the silver recovered from it would alone 

 represent at least £42,000, or a nett profit of about £33,500; 

 and the produce of silver from a similar amount of Cornish ores 

 would be much greater. The average Spanish burnt ore con- 

 tains from 15 to 13 dwts. of silver per ton. The above calcu- 

 lation does not include the value of the copper, which has been 

 shown to be considerable, and recoverable by nearly the same 

 process. 



For particulars of the process, I refer you to Mr. J. A. 

 Phillips's able paper on the subject, read before the Chemical 

 Section of the Society of Arts, Feb. 25, 1876, and to which I am 

 indebted for the above facts. I had hoped to have received 

 specimens illustrative of the process to place on the table before 

 jou, through the kindness of Mr. Mac Ivor, who so ably directs 

 the works now in operation at the Emmens United Mines, near 

 Callington, but from some cause the illustrative series of 

 specimens have not arrived in time for the meeting. . 



Another new source of industry which we are glad to welcome, 

 is the manufacture of Vitrified Bricks, of all shapes and kinds, 

 from common killas ; a material which abounds in this county, 

 and which has hitherto been regarded as worthless. The killas 



