METALS. 



METEORIC IROX. 



461 



mixture of arsenious acid and charcoal powder ; 

 but by repeating the experiment Prof. Cooko 

 found these crystals to be merely arsenious 

 acid, colored by particles of metallic arsenic in 

 mechanical mixture, like the sand in the crys- 

 tals of Fontaineblean sandstone. But when 

 rhomboliedral crystals of ar>eiiic prepared by 

 sublimation in the usual way, afterwards kept 

 under water deprived of air by boiling, and 

 just before using dried in a current of hydro- 

 gen, were sublimed in a flask filled with hydro- 

 gen, the crust produced was found to be stud- 

 ded with distinct octahedral crystals, having a 

 grayish color and a bright metallic lustre, but 

 of microscopic dimensions. These were satis- 

 factorily ascertained to belong to the cubic sys- 

 tem ; and the absence of arsenious acid was also 

 proved by experiment. The mirror obtained 

 by the reduction of arseniuretted hydrogen gas 

 in a current of hydrogen gave similar results. 

 Microscopic octahedral crystals of antimony, 

 frequently modified by the faces of the cube, 

 and in one case at least by those of the rhom- 

 bic dodecahedron, were obtained by reducing 

 antirnoniuretted hydrogen in the same way ; 

 and Prof. Cooke is of opinion that in the mir- 

 rors of arsenic and antimony obtained by 

 Marsh's test these metals are always in the oc- 

 tahedral modification. The best crystals were 

 obtained by resubliming the metallic mirrors in 

 a slow current of hydrogen, in which way the 

 crystals could be entirely isolated on the surface 

 of the glass tube. As to zinc, the only described 

 crystals of the pure metal belonging to the cu- 

 bic system are some alleged pentagonal dode- 

 cahedra obtained by M. Favre, of which, how- 

 ever, no measurements were made, and which 

 have been doubted by Gustav Rose. The oc- 

 currence, however, of brass crystallized in reg- 

 ular octahedra, and the accidental production of 

 brilliant octahedral crystals containing 81 '18 per 

 cent, of zinc and 18'82 arsenic, as a furnace pro- 

 duct, seem to show that, even if incapable of 

 crystallizing in such forms when alone, a small 

 proportion of an octahedral metal alloyed with 

 it will predispose it to assume them. Prof. Cooke 

 remarks that a certain amount of impurity 

 seems to favor the crystallization of metals, 

 and instances the beautiful lead crystals con- 

 taining a little antimony from Clausthal, and 

 antimony crystals with a little lead, as well as 

 similar facts in the case of bismuth. 



On the amount of Lead in some Silver Coins. 

 Messr?. Eliot and Storer, finding in the course 

 of their examination of the impurities of zinc, 

 that the zinc employed in the U. S. Mint con- 

 tained half of one per cent, of lead, were in- 

 duced to examine the percentage of lead in 

 American and foreign silver coin : 



Kind of Coin. Percent, of Lead In Coin. 



1 American half dollar of 1S24 0.301 



20 " five-cent pieces of 1S53 0.209 



10 " ten-cent pieces of 1854 



2 " twenty-five cent pieces of 1S5S 0.231 



Fine silver from f. S. Assay Office. New York, 1S60.. 0.1C1 



1 Spanish dollar of 179:5. Carolus IV 0.056 



1 Mexican dollar of 1829 0.043 



2 English shillings of 1816 0.4S5 



1 French five-franc piew of 1852, Napoleon III 0.428 



In order to ascertain whether the zinc used 

 in the reduction of the silver was the probable 

 source of the lead in the American coin, the 

 authors calculated the amounts which would 

 be introduced by the use of the two qualities 

 of Vieilla Montagne zinc analyzed by them, 

 and from that the best would have given O.lob 

 per cent, of lead in the coin, and the second 

 quality 0.268 per cent., between which limits 

 all their analysis (except that of the half dollar 

 of 1824) would fall. They are far, however, 

 from affirming this to be the exclusive cause 

 of this impurity, as some may probably be de- 

 rived from the lead vats in which the chlo- 

 ride of silver is reduced, or from the sul- 

 phuric acid used. The process of separating 

 lead and silver is said to have been less per- 

 fectly executed in the ages of antiquity than at 

 present. 



Alloys of Aluminum. Alloys of aluminum 

 have been lately prepared, which seem suscep- 

 tible of many applications in the arts. The 

 bronze, composed of 10 per cent, of aluminum 

 and 90 per cent, of copper, which appears the 

 most valuable, has a color near that of gold, 

 and takes a polish equal to that of steel. 

 Drawn into No. 16 wire, the breaking strain 

 of copper was 418 Ibs., of iron 616 Ibs., and of 

 aluminum bronze 955 Ibs., a tenacity almost 

 equal to the best steel wire. As regards hard- 

 ness, a groove for the guide-box of a locomo- 

 tive made of it was compared with one made 

 of steel, and after six months' wear, gave 

 equally good results. It rolls at all tempera- 

 tures, from cold up to a bright cherry red, but 

 best at as high a temperature as possible, short 

 of fusion. In rolling it cold, if re-heated and 

 then cooled by plunging in water, it works 

 better than if simply re-heated, without dip- 

 ping. 



New Alloy. A new alloy has been produced 

 by M. Aich, of Brussels. It presents the ad- 

 vantage of working as well cold as hot ; can 

 be forged without losing its cohesion ; melts 

 very readily, and can be afterwards hammered, 

 rolled, or punched. It is cheaper than brass or 

 pure copper, and may advantageously super- 

 sede them for ship-building and many other 

 purposes, as it is more tenacjous and not so 

 oxidizable. It consists of 60 parts copper, 38'2 

 parts zinc, and 1*8 parts iron. 



METEORIC IRON". In the year 1846 a mass 

 of iron of over 15 pounds (542 pounds avoir- 

 dupois) was found 7 versts (4.6 miles) from the 

 station Mariinskoji (in the government of Tula) 

 on the Moskaw-Tula road (54 35' JS". lat. and 

 37 34' E. of Greenwich.) It was sold for 4 

 roubles (3 dollars) to the Myschega Iron Works 

 in the neighborhood, where the greater portion 

 of it was worked up into axles, wagonsprings, 

 grapnels, and other implements, until in 1857 

 Dr. Auerbach learned of its existence, and 

 saved the remainder from destruction. He has 

 given the first notice of it, and in a preliminary 

 analysis of it found the mass to contain : iron, 

 93.5," nickel, 2.5, traces of tin, and 0.9 schreiber- 



