206 ANNUAL OF SCIENTIFIC DISCOVERY. 



artificially polished or fused, and then clean it perfectly with a piece of cham- 

 ois leather, the surface, when breathed upon, will exhibit, in the most brilliant 

 manner, all the colors of thin plates. If we breathe through a tube, the colors 

 will be arranged in rings, the outermost of which is black, corresponding 

 to the center of the system of rings formed between a convex and a plane 

 surface. In repeating this experiment on the surfaces of other bodies, Sir 

 David found that there were several on whose surfaces no colors were pro- 

 duced. Quartz exhibited the colors like glass, but calcareous spar and several 

 other minerals did not. In explaining this phenomenon, the author stated 

 that the particles of the soap, which are dissolved by the breath, must either 

 enter the pores of the bodies or form a strongly adhering film on their surface. 

 This property of appropriating, temporarily, the particles of soap, becomes a 

 new distinctive character of mineral and other bodies. 



PREPARATION OF AMMONIA IN THE SMELTING OF IRON. 







The following suggestions from the London Mining Journal, by Mr. T. H. 

 Leighton, are worthy of consideration : 



" The vapors which escape from iron blast furnaces may be regarded simply 

 as the atmosphere highly charged with carbon, or as a mixture of carbonic 

 oxyd, cyanogen, and nitrogen. "When steam, at a sufficiently high tempera- 

 ture, and air excluded, is mingled with these gases, the oxygen of the steam 

 decomposes the cyanogen, and converts the carbonic oxyd into carbonic acid, 

 while the hydrogen and nitrogen combine to form ammonia ; thus carbonate 

 of ammonia will result ; but as it may prove difficult to condense this efiectu- 

 all}*, if the vapor of ammonia were conveyed into a chamber charged with an 

 insoluble lumpy material, so arranged that the ammonia, in ascending would 

 come in contact with a cold solution of salt trickling down, carbonate of 

 soda and muriate of ammonia might be at once obtained. If, however, an 

 ample supply of sulphate of iron could be procured, it would be more advis- 

 able to fix the ammonia by means of sulphuric acid expelled from sulphate 

 of iron, because at the same time, pure oxyd of iron would be produced, 

 which would prove valuable in the subsequent forging of iron. Alkali refuse 

 should be composed of sulphuret of calcium and coke dust. When this is 

 acted upon by steam with sufficient heat, the oxygen of the steam converts 

 the calcium into lime, while the sulphur and hydrogen pass off as sulphuretted 

 hydrogen. When the latter is mingled with the vapors from a dense purely 

 carbonaceous fire, consisting of carbonic oxyd and nitrogen, the latter com- 

 bines with the sulphuretted hydrogen, and forms sulphuret of ammonia. 

 If these vapors are then partially cooled down, and a large quantity of cool 

 air admitted, the carbonic oxyd becoming carbonic acid, combines with 

 the ammonia, and disengages sulphur ; thus carbonate of ammonia and sub- 

 limed sulphur might be obtained. If, on the other hand, the heat of the va- 

 pors is maintained, and a large quantity of heated air thrown in, the sulphuret 

 of ammonia is converted into sulphite, which rapidly passes into sulphate 

 of ammonia, by means of which more salt may be decomposed ; and thus 

 alkali refuse may be brought to yield sulphate of soda, muriate of ammonia, 



