142 Chronicles of Science. [Jan., 



cliohe-damp, wtich it would be necessary to remove. This plan, 

 like many others which are from time to time brought forward, 

 evidently originated with one who was but imperfectly acquainted 

 with the conditions under which fire-damp is formed in a colliery. 



The Pitch Lake of Trinidad ever and anon claims the attention 

 of the public. At one time it is introduced as the source from 

 which all the varieties of mineral oil, parafline, and asphaltum can 

 be obtained. At another period it is to be employed to give greater 

 illuminating power to our coal-gas, and some experiments of the 

 Hon. Captain Cochrane, made at Woolwich, were highly favourable. 

 Now we have the pitch of Trinidad coming before us as an ingi-e- 

 dient in artificial fuel for steamers. The bitumen is mixed with a 

 certain quantity of charcoal; it is ground, and then made into 

 bricks. Experiments made on board H.M.S. ' Gannet,' Commander 

 Chimmo, appeared to show that it possessed many valuable pro- 

 perties, but the amount of ash, arising from the earthy matter mixed 

 with the petroleum, was somewhat objectionable. This can, how- 

 ever, in all probability, be obviated by greater attention in the pro- 

 cess of manufacture. 



The Sicilian sulphur mines have been long known. More than 

 600 mines have been at work, and at least 200 worked out and 

 abandoned. The mining is of the most primitive character, the 

 use of machinery being extremely limited. Not less than 22,000 

 people are occupied in working those mines, and the result is the 

 production of sulphur to the value of not less than 17,600,000 francs 

 per annum. The sulphm- ores of Spain are now largely imported 

 into this country, and during the year not less than 500 tons of 

 copper have been separated from sulphur-ash, after the sulphur 

 has been expelled by burning, although the pyrites does not contain 

 more than from 1 to 2 per cent, of that metal. 



Metallurgy. 



There is but little worthy of notice in the Metallurgy of the 

 quarter, beyond the cheerful intelligence that in every branch there 

 are evidences of a very decided improvement. 



One process — that of Mr. Heaton — for the conversion of iron 

 into steel, has been attracting considerable attention. Experiments 

 have been in progress at Langley Mills, and the results are certainly 

 of great promise. The process is conducted as follows : — Cast iron 

 of any quahty is first melted in a common iron-foundry cupola with 

 coke fuel. A known quantity of the liquid iron — usually about a 

 ton — is tapped out into an ordinary crane ladle, which is swung 

 round to the side of the converter. This latter is a tall cylinder of 

 boiler-plate, opfu at the bottom, between which and the floor a 

 space is left. The converter has a fire-brick lining, and terminates 

 in a conical covering, out of which an iron funnel opens to the 



