1865.] Mining, Mineralogy, and Metallurgy. 491 



grains, and required no less than 2,853 sheets to make one inch in 

 thickness ; and eventually they made another sheet of 48 surface 

 inches, which weighed 25 grains, and required 2,950 sheets to make 

 one inch in thickness. At the Pontardawe Tin Works there was 

 subsequently made a sheet having a surface of 115'17 inches, weigh- 

 ing 60 grains. This was a trifle heavier than the Marshfield sheet, 

 but Pontardawe claims 3,799 sheets to make a thickness of one inch. 



All this has, however, been outdone at the Upper Forest Tin 

 Works, near Swansea, of Messrs. W. Hallam and Company. At their 

 mills, a sheet of iron has been produced with 55 inches surface, and 

 weighing but 20 grains, which, being brought to the standard of 

 44 inches, is but 16 grains, or 30 per cent, less than any previous 

 effort, requiring at least 4,800 sheets to make one inch in thickness.* 



Steel made at the Ebbw Vale works, by Mr. Parry's patent, has 

 been rolled into exquisitely thin plates. The thinnest is said to have 

 been *001 in thickness, perfectly tough, smooth, and free from holes. 



The Koyal Academy of Sciences of Belgium has given its gold 

 medal to Captain Caron, as the author of the best work on the con- 

 stitution of steel. M. Straas, who was chairman of the committee 

 appointed to examine the essays sent in, makes high commendation 

 of Captain Caron's work. He expresses his entire concurrence in his 

 opinion, that iron, in passing into steel, does not take up any nitrogen 

 in addition to that which it already contained. Steel, M. Straas 

 remarks, is essentially composed of iron and carbon, and owes its 

 qualities or its defects to two different causes — the state of carbon in 

 the metal, or the nature of the foreign bodies which debase it. 

 Whenever steel is good, its carbon can, under the influence of temper- 

 ing, combine with the metal, and give us a hard, brittle metal, which 

 further tempering renders supple and elastic. When steel becomes 

 hard after undergoing several heatings, it is due to its carbon having 

 been burnt or separated from the iron, and tempering will not then 

 regenerate the combination. This separation is due to the presence of 

 foreign bodies, more especially silicium. M. Straas concludes by 

 saying, " Captain Caron's Essay is undoubtedly the resume of long 

 and glorious labours, put forth with a simplicity and lucidity which 

 greately enhance their merits." There will be many a dissentient 

 voice in this country to the somewhat dogmatic statements of 

 M. Straas. 



PHYSICS. 



Light. — Spectrum-analysis has recently performed a somewhat im- 

 portant service to chemistry. Besides the well-known chemical 

 elements, and those new ones, such as Caesium, Eubidium, Thallium, 

 and Indium, which have after a long or short probation been definitely 

 admitted into the family of elementary bodies, there are several sub- 

 stances waiting, as it were, on the threshold admitted as elements by 



* Most of these particulars have been obtained from the 'Mining Journal.' 

 The remarks on steel plates are from ' The Engineer.' 



