Mermaid 

 Meteorites 



SCIENTIFIC SIDE-LIGHTS 



440 



creatures [the dugong] (as big or bigger 

 than human beings), which have a habit of 

 raising themselves up vertically out of the 

 water, when they present a very startling 

 appearance to an unscientifically critical 

 eye. Astonished travelers beheld beings 

 with rounded, human-looking heads, show- 

 ing their body down to the bust out of the 

 water, displaying a pair of rounded promi- 

 nent breasts, and not seldom holding a baby 

 in their arms. After remaining some time 

 in this attitude, they would suddenly dive, 

 and then a tail like a fish's became exposed 

 to view. Small wonder, then, that sailors 

 should imagine they were beholding crea- 

 tures half woman and half fish, for the 

 vivacity of a sailor's imagination is pro- 

 verbial. MIVAKT Types of Animal Life, ch. 

 11, p. 303. (L. B. & Co., 1893.) 



2152. METAL USED AS STONE 



Transition from Stone to Bronze. On the 

 whole, tho it would seem that they [the 

 American Indians] sometimes at any rate 

 softened the metal by heat, we have not, I 

 think, at present any sufficient evidence that 

 the redskins were acquainted with the art of 

 casting. This is the more surprising be- 

 cause, as Schoolcraft tells us, " in almost all 

 the works lately opened there are heaps of 

 coals and ashes, showing that fire had much 

 to do with their operations." Thus, tho 

 they were acquainted with metal, they did 

 not know how to use it; and, as Professor 

 Dana has well observed in a letter with 

 which he has favored me, they may in one 

 sense be said to have been in an age of 

 stone, since they used the copper, not as 

 metal, but as stone. This intermediate con- 

 dition between an age of stone and one of 

 metal is most interesting. AVEBUEY Pre- 

 historic Times, ch. 8, p. 240. (A., 1900.) 



2153. METALS, COMBUSTIBLE 



Burning of Iron and Zinc. The rusting of 

 iron is, to all intents and purposes, the slow 

 burning of iron. It develops heat, and, if 

 the heat be preserved, a high temperature 

 may be thus attained. The destruction of 

 the first Atlantic cable was probably due to 

 heat developed in this way. Other metals 

 are still more combustible than iron. You 

 may light strips of zinc in a candle flame 

 and cause them to burn almost like strips of 

 paper. TYNDALL Lectures on Light, lect. 1, 

 p. 5. (A., 1898.) 



2154. METALS, DIFFUSION OR 

 FLOWING OF Gold Sinking into Copper 

 Old Coins Buried Increase in Purity. It is 

 well known to the jeweler that articles of 

 copper, plated with gold, lose their 'bril- 

 liancy after a time, and that it can be re- 

 stored by boiling them in ammonia; this 

 effect is probably produced by the ammonia 

 acting on the copper, and dissolving ^off its 

 surface so as to expose the gold, which, by 

 diffusion, has entered into the copper. 



A slow diffusion of one metal through an- 

 other probably takes place in cases of alloys. 

 Silver coins, after having lain long in the 



earth, have been found covered with a salt 

 of copper. This may be explained, by sup- 

 posing that the alloy of copper, at the sur- 

 face of the coin, enters into combination with 

 the carbonic acid of the soil, and being thus 

 removed, its place is supplied by a diffusion 

 from within, and in this way it is not im- 

 probable that a considerable portion of the 

 alloy may be exhausted in the process of 

 time; and the purity of the coin be consid- 

 erably increased. HENRY Capillarity of 

 Metals, Scientific Writings, p. 229. (Sm. 

 Inst., 1888.) 



2155. Silver Sinking 



into Pores of Copper Recovery by Acid 

 Man of Science Instructs "Practical" Work- 

 men. [To test his theory of metals] he 

 [Henry] inquired of Mr. Cornelius, of Phila- 

 delphia, if in the course of his experience in 

 working silver-plated copper in his extensive 

 manufactory of lamps he had ever observed 

 the silver to disappear from the copper when 

 the metal was heated. The answer was that 

 the silver always disappears when the plate 

 is heated above a certain temperature, leav- 

 ing a surface of copper exposed ; and that it 

 was generally believed by the workmen that 

 the silver evaporates at this temperature. 



Professor Henry suggested that the silver, 

 instead of evaporating, merely sunk into the 

 pores of the copper, and that by carefully 

 removing the surface of the latter, by the 

 action of an acid the silver would reappear. 

 To verify this by experiment, Mr. Cornelius 

 heated one end of a piece of thick plated 

 copper to nearly the melting-point of the 

 metal; the silver at this end disappeared, 

 and when the metal was cleaned by a solu- 

 tion of dilute sulfuric acid, the end which 

 had been heated presented a uniform surface 

 of copper, whilst the other end exhibited its 

 proper coating of silver. The unsilvered end 

 of the plate was next placed, for a few min- 

 utes, in a solution of muriate of zinc, by 

 which the exterior surface of copper was re- 

 moved, and the surface of silver was again 

 exposed. This method of recovering the sil- 

 ver (before the process of plating silver by 

 galvanism came into use) would have been 

 of much value to manufacturers of plated 

 ware, since it often happened that valuable 

 articles were spoiled, in the process of sol- 

 dering, by heating them to a degree at which 

 silver disappears. HENRY Capillarity of 

 Metals, Scientific Writings, p. 228. (Sm. 

 Inst., 1886.) 



2156. METALS THE GIFT OF VOL- 

 CANOES Brought from Depths of Earth. 

 But it is not only the finely crystallized 

 minerals and gems which we owe to volcanic 

 action. The various metallic minerals have 

 nearly all been brought from deep-seated 

 portions of the earth's crust and deposited 

 upon the sides of rock-fissures by the agency 

 of the same volcanic forces. It is these 

 forces which have, in the first instance, 

 opened the cracks through the solid rock- 

 masses ; and, in the second place, have 

 brought the metallic sulfids, oxids, and 



