TRANSACTIONS OF THE SECTIONS. 59 



treatment with water. A very pure sulphur, almost absolutely free from arsenic, 

 is obtained by this mode of working, which has been carried out successfully by 

 various manufacturers ; but the quantity of sulphiu- obtained is far short of that 

 contained in the waste, and the author considered the problem still remained as an 

 exercise for ingenuity and perseverance. The former mode of obtaining copper and 

 silver from the burnt residua of coppery pyi-ites which had been used for yielding 

 sulphur to manufacture sulphuric acid, has been superseded by a process devised 

 by Mr. Henderson, which consists in mixing a small proportion of salt with burnt 

 pyrites, previously gi-ound to a fine powder, exposing this mixture to a low red 

 heat, and passing through it a current of air. By these means the small poi-tion of 

 sulphur which has escaped being consumed in the biu-nt pp'ites becomes oxidized, 

 producing sulphate of iron, which decomposes common salt, yielding chloride of 

 copper and sulphate of soda, which are obtained in solution on lixiviating the pro- 

 duct with water. The copper is then precipitated from the solution by means of 

 iron, and is obtained in the metallic state. A large quantity of oxide of iron is 

 obtained as a residuum from the lixiviation. This is sold to the iron-smelters for 

 the production of iron. These operations are carried out very extensively by the 

 Tharsis Metal Company at Glasgow, Newcastle, and Widnes ; and at the Widnes 

 Metal Company, ^h. J. A. Phillips has carried out successfully a process invented 

 by Mr. Claudet, of Loudon, for exti-acting gold, silver, and lead from the burnt 

 residua of coppery pyrites. Li the year 1861, diuriug the negotiation of the French 

 Treaty of Commerce, it was estimated that the total quantity of salt decomposed 

 in Great Britain for the production of soda was 260,000 tons per annum. Of this 

 quantity 125,000 tons were decomposed in what is called the Newcastle district, 

 and 1.35,000 tons in the Lancashire district. According to the returns of the Alkali- 

 Manufacturers' Association for the year 1869, the total quantity of salt decomposed 

 for the manufacture of soda was 326,000 tons, thus .showing an increase of 66,000 

 tons, or 25 per cent, on the total. Of this quantity the decomposition in the New- 

 castle district in 1869 was 142,000 tons, which, being compared with 125,000 tons 

 in 1861, shows an increase of 17,000 tons, or 13-6 per cent. The decomposition in 

 the Lancashire district is retm-ned as 184,000 in 1869, against 135,000 tons in 1861, 

 showing an increase of 49,000 tons, or 36 per cent. Thus the Lancashire district 

 in 1860 exceeds by 30 per cent, the total quantity decomposed in the Newcastle 

 district during the same year. One of the most important applications of soda to 

 other manufactures is that of the production of soap. In the year 1852, when the 

 excise duty was finally abolished, the total production in Great Britain was equal 

 to 1600 tons per week, less than one half of which was produced in the Lancashire 

 district. The present production in the Lancashire district is fully equal to the 

 total production in 1852. Regarding the immense number of manufactories at 

 work in Lancashire for the production of chemical substances to be used in bleach- 

 ing, dyeing, calico-printing, &c., the conclusion was arrived at that Lancashire is 

 the largest seat of chemical manufactiu-es in this country. 



0)1 a Metliod for the Determination of Sulphur in Coal-gas. 

 By A. Veknojt HAHcorRT, F.E.S. 



This paper gave a description of a piece of apparatus, which was exhibited in 

 action, and an account of the results obtained with it. The apparatus consisted of 

 a small Bimsen burner, whose nozzle passed into a glass cylinder, closed at both 

 ends, through which air was drawn by an aspirator. The products of combustion 

 were washed with an ammoniacal solution of copper dm-ing their passage through 

 a system of bulbs. A Woulfe's bottle, tilled with fragments of pimiice steeped in 

 ammoniacal solution of copper, served to purify the air at its entrance, and also to 

 charge it with ammonia. 



The apparatus had been tested by passing through it carbonic acid mixed with 

 a known amount of sulphurous acid, and also by washing a second time the gases 

 leaving it. Satisfactory results had been obtained. Moreover two or more ana- 

 lyses of the same sample of gas gave numbers which were closely concordant. 



