JlAKOH 2, L8S3.1 



SCIENCE. 



105 



sleepers in iron and steel, which are now almost 

 wholly used in Germany, the process is likely to prove 

 of much advantage. For fountains, railings, and all 

 architectural work, the process is invaluable; and 

 iron may now be used in many instances instead of 

 bronze. Tlie cost lias been carefully estimated at 

 two dollars per ton ; and this may be reduced by giving 

 several furnaces in charge of one workman, and by a 

 better system of taking the articles out than that in 

 use when tlie estimate was made. Tests have been 

 made as to the effect of tlie process on the strength 

 of the metals, M'ith the result that no alteration was 

 detected in the strength. Theoretically one would 

 suppose that iron and steel would be somewhat tough- 

 ened, as the teiulency of the process is to anneal, and 

 would, no doubt, if continued long enough, render 

 some classes of cast-iron malleable. A very thin 

 article, if excessively coated, might probably be 

 weakened, due to the fact that the coat of magnetic 

 oxide would form an appreciable percentage of the 

 bulk of tlie article; but that, of course, is a very 

 extreme case, and one which is not likely to ever 

 occur in practice. 



Note on the jacketing of roasting cylinders 

 at Deloro, Canada. 



BT PKOF. K. p. BOTnWELI, OF NEW YORK. 



The speaker said, that he merely desired to place 

 on record the fact tliat he had been using roasting 

 cylinders jacketed, to prevent any one from taking 

 out a patent on the idea. He did not wish to deprive 

 any one of the privilege of using it, but he also did 

 not wish to be deprived of that privilege himself. In 

 the roasting of arsenical sulpluirets he liad emjiloyed 

 what is commonly known as the White and Uowell 

 cylinders, of plain boiler-iron, with fire-brick lining 

 and shelves. He used two of tliein ; the ore passing 

 from one to tlie other through a pipe, without losing 

 its lieat. Tlie first cylinder is 30 feet long and 5 feet 

 in diameter, and takes out a large part of the arsenic 

 and sulphur. The second is 24 feet long and a little 

 less than 4 feet in diameter, in which the roast 

 is finished. The two make a complele roast for chlo- 

 rinating, and give from 94% to 98% of the gold. But 

 these cylinders r.adiated an immense amount of lieat, 

 too mucli to allow the tempei-alure to be kept suffi- 

 ciently higli to obtain a complete ro.ast. This loss by 

 radiation has been avoided by jacketing. A sheet- 

 iron jacket is placed arovmd the cylinder, leaving an 

 air-sjiace of two inches; outside of tliis is another' 

 jacket with a space of two and a lialf inches, which is 

 filled with mineral or slag wool; this is mixed with 

 plaster of paris, and further covered with roofing- 

 paper bound on with wire. Immediately upon the 

 use of this apparatus there was noticeable a tremen- 

 dous reduction in the consumption of fuel required, 

 and a remarkable increase in tlie .amount of ore 

 roasted. As thus made, it even resulted in heating 

 the upper portion of the first cylinder too mucli, and 

 roasting too quickly, not leaving in the ore tlie sulphur 

 necessary for the treatment in the second cylinder. 

 The trouble was remedied by removing cijilit feet of 

 the jacket around the upper part of the cylinder. 



Geological relations of the topography of the 

 South Appalachian plateau. 



BY PBOF. W. C. KERB OP WASUINOTON. 



By aid of a rough black-board sketch of the Blue 

 Eidge and Smoky Mountains, the backbone of tlie 

 system, the speaker showed from a study of the rivers, 

 that the plateau has been gradually travelling west- 



ward. A series of spurs are thrown out by the Blue 

 Ridge on the east, making a drainage system of cross 

 valleys; here are the head-waters of the Tennessee 

 river, which force their way through the great escarp- 

 ment of the plateau, and through the Smoky Moun- 

 tains, which in some places attain an altitude of 6,000 

 feet. This is a very remarkable and curious fact. 

 The cafion througli which the waters break is 4,000 

 feet deep, and has rocky sides not easily removed or 

 eroded. A study of the situation sliows, that since the 

 establishment of tlie water-system there has been slow 

 and steady rise of the mountain chain, the waters 

 at the same time cutting their way down. There is 

 another curious feature in this connection: the Ten- 

 nessee river runs between tliis chain and the Cumber- 

 land ridge, and it would naturally be supposed tliat 

 tliere is a rise from the west side of the river to the 

 Cumberland. But observations with the barometer 

 show, that there is really a continuous descent from 

 the top of the Stnoky Mountains to the base of the 

 Cumberland chain, and here we have a river running 

 at a higher level tlian its tributaries. The explana- 

 tion is simply, that the Cumberland ridge has been 

 gradually sinking since the establishment of the water- 

 system. 



The collection of flue-dust at Ems. 



BY DR. T. EGLESTON OF NEW YORK. 



In the treatment of silver from lead-ores, this sub- 

 ject is a matter of growing importance in Ems at the 

 works under the charge of Herr Fjeidenbach, and of 

 some importance here. In 1874 it was found at Ems 

 that there was a considerable loss of product by the 

 dry metliod, and the wet method was substituted; 

 and still the loss of dust was much greater than had 

 been supposed. There were three difficulties to over- 

 come: to arrest the material carried off by meclianical 

 means, to collect the material which is volatilized, — 

 these two problems being comparatively easy of solu- 

 tion; but, when the collection was made, it was an- 

 other thing to Iceep the material collected where it 

 was, and prevent its further loss. Tlie works are 

 located on a plateau and hill. They run first down 

 the valley, and then, turning on themselves, up the 

 hill, continuing in a straiglit line to the top, where 

 there is a chimney. In 1874 the length of the flue 

 was 460 m., and it was furnished witli the old style 

 of condensing-chambers. The canal was then length- 

 ened to 2,000"m., and carried to the flue 200 m. above 

 the bed of the river. It was noted at once, that there 

 was an immediate precipitation of flue-dust, much 

 larger tlian liad been anticipated, but still not effect- 

 ing a sufficient reduction of the loss. An examination 

 of the pipes led to the adoption of iron pipes, with the 

 lowerpart terminating in zigzags 75 cm. deep, through 

 which, by means of a door and close-fitting tube, the 

 dust could be drawn out of the flue. This dust was 

 rich, and the results of the method were satisfactory 

 until the assays showed that much matter was lost by 

 volatilization. Ficidenbach soon found that the old- 

 style arched flue was the worst that could be used; 

 for, while its form gave strength to resist pressure 

 from without, it also rendered it weak against pressure 

 from within, and the gases found a comparatively 

 easy means of exit through it. The flues were then 

 made rectangular, bound together with iron, and made 

 as tight as possible to prevent the escape of vapors. 

 This form is now adopted everywhere. In the length 

 of the flue was a series of condensation-chambers, 

 but these were found to give no great results. The 

 flue was now 2,000 ra. in length, with an area of 

 42,650 D m., and had cost 25-5,000 marks. A series of 

 condensation-houses was built beyond the chimney, 



