TRANSACTIONS OF SECTION B. 547 



again attracted by tlie circumstance that some mines in Central Spain were offered 

 to me which produce copper ores rich in silver and a small quantity of cobalt, and 

 it was desirable if possible to demise some cheap and simple process whereby these 

 metals could be perfectly separated from each other. 



A series of experiments led to the adoption of bisulphate of soda for this pur- 

 pose, which gives for silver very perfect results with reguluses. I have not been so 

 successfid with ores, for obvious reasons. 



Therefore, on November 3, 1879, I took out a patent, No. 4481 of that year, 

 * for treating certain ores and reguluses,' and I have since made a good many 

 experiments which, I regret to say, are principally crucible experiments, not having 

 at hand a.nj reguluses rich in silver to work with on a large scale. 



My last results are, however, so exact that I venture now to lay them before 

 the Chemical Section of the British Association. 



The ore I liad to deal with was from Spain, and contained a very large 

 quantity of arsenic, the calcination of the ore leaving a loss of 28 to- 37 per cent. 



I found in my first experiments with this new process that both arsenic and 

 antimony \erj much interfered with the results obtained. I therefore continued 

 the calcination until I had arrived at what is technically known as calcined ' dead.' 

 My aim was to produce a regains of about 50 per cent, copper, and to accomplish 

 this I added a corresponding proportion of the ordinary Spanish pyrites, rich in 

 sulphur, and this produced a regulus containing not more than 1 per cent, of 

 arsenic, but contained besides a small quantity of lead which existed in the Spanish 

 ore I had to deal with. 



The reguhis as produced gave 285 ozs. 16 dwts. 16 grs. of silver per ton of 

 regulus, and of copper 42 per cent. 



In previous experiments I had come to the conclusion that, provided the 

 regulus did not contain much arsenic or antimony, as good and even better results 

 were obtained from the raw regulus. To test this, equal quantities of the same 

 regulus — 1st, calcined 'dead'; 2nd, half-calcined, 3rd, raw regidus — each with 

 20 per cent, of bisulphate of soda, were added. The three crucibles were placed in 

 the same fi-e and calcined at a gradually increasing heat, and finished at a bright 

 red heat when gases had ceased to be given off. This occupied one hour and 

 twenty minutes. The results were as follows : — 



ozs. dwts. grs. 

 1st silver soluble 07615 per cent. =248 16 4 

 2nd „ „ 0-8265 „ =269 19 20 



Srd „ „ 0-8765 „ =286 6 12 



This last result I consider very perfect, and I regret much that I have not been 

 in a position to place before you anything more than laboratory experiments. 



I 



TUESDAY, AUGUST 31. 



The following Papers were read :— 



1. Further Notes on Petroleum Spirit and Analogous Liquids. 

 By Alfred H. Allen, F.G.8. 



In a paper read before the Section at the Sheffield Meeting, the author de- 

 scribed cej tain tests by which the ordinary ' benzoline ' or petroleum spirit of 

 commerce could be distingiushed from and approximately estimated when in 

 admixture with coal-tar naphtha or crude benzene. 



Extending his researches in this direction, the author now described methods 

 by which the above-named products could be distinguished from the very similar 

 liquid known as ' shale naphtha,' obtained as a secondary product in the manu- 

 factiure of paraffin wax from bituminous shale. 



N n2 



