METALS 



239 



A process invented by M. Abate, and published by him 

 in 1851. It consists of printing from engraved wood-blocks upon metallic surfaces, 

 so as to produce imitations of figures and ornaments inlaid in wood. This effect he 

 obtained by using, as a printing menstruum to wet the block with, solutions of such 

 metallic or earthy salts as are decomposed when brought into contact with certain 

 metals, and produce, through an electro-chemical action, an adhesive precipitate of a 

 coloured metallic oxide, or any other chemical change upon the metal. 



IVIETAXiIiOXDS. Davy proposed this name for sodium and potassium, and other 

 substances of which the metallic character was not well defined. Berzelius used 

 the term to distinguish the non-metallic elementary substances from the metals. 

 Dr. Apjohn published a ' Manual of the Metalloids,' in which he adopted this 

 meaning. The word metalloid signifying like a metal, its use in this sense is unfor- 

 tunate. 



METAXiXiURGY. (Huttenkunde, Ger.) The art of extracting metals ffom their 

 ores. Under the heads of the different metals respectively, the metallurgical processes 

 to which they are subjected are given. See ANTIMONY, COPPER, GOLD, IRON, &c. 

 A full description of the processes of preparing the minerals for the operations of the 

 metallurgist will be found under the head of DRESSING OF ORES. 



When it is intended to wash certain ores, an operation founded on the difference 

 of their specific gravities, it may happen that by slightly changing the chemical 

 state of the substances that compose the ore, the earthy parts may become mdre easily 

 separable, as also the other foreign matters. With this view, the ores of tin are 

 subjected to a roasting, which, by separating the arsenic and oxidising the copper 

 which are intermixed, furnishes the means of obtaining, by the subsequent washing, 

 an oxide of tin much purer than could be otherwise procured. In general, however, 

 these are rare cases ; so that the washing almost always immediately succeeds the 

 picking and stamping ; and the roasting comes next, when it needs to be employed. 

 See BOASTING ORES. 



ItXETAXiS (Metaux, Fr. ; Metalle, Ger.) are by far the most numerous class of 

 undecomposed bodies in chemical arrangements. They amount to 51 ; of which 7 

 form, with oxygen, bodies possessed of alkaline properties : these are, 1. potassium ; 

 2. sodium; 3. lithium (bases of the alkalis) ; 4. barium; 5. strontium; 6. calcium; 

 7- magnesium (bases of the alkaline earths, for even magnesia, the last and feeblest 

 base, tinges turmeric brown, and red cabbage green). The next seven metals form 

 with oxygen the earths proper : they are, 8. yttrium; 9. glucinum; 10. aluminium; 

 11. zirconium; 12. thorium; 13. erbium; 14. terbium. The remaining 37 maybe 

 enumerated in alphabetical order, as they hardly admit of being grouped into sub- 

 divisions with any advantage. They are as follow: 15. antimony; 16. arsenic; 

 17. bismuth; 18. cadmium; 19. cerium; 20. chromium; 21. cobalt; 22. copper; 

 23. didynmim ; 24. gold ; 25. iridium ; 26. iron ; 27. lead ; 28. lanthanum ; 29. 

 manganese; 30. mercury; 31. molybdenum; 32. nickel ; 33. niobium; 34. osmium; 

 35. palladium; 36. platinum; 37. rhodium; 38. ruthenium; 39. silver; 40. tanta- 

 lum; 41. tellurium; 42. tin; 43. titanium; 44. tungsten; 45. vanadium ; 46. ura- 

 nium ; 47. zinc ; and lately by spectrum analysis the following have been discovered, 

 48. coesium; 49. indium; 50. rubidium; and 51. thallium. 



1. They are all, more or less, remarkable for a peculiar lustre, called the metallic 

 lustre. This property of strongly reflecting light is connected with a certain state of 

 aggregation of their particles, but is possessed, superficially at least, by mica, animal 

 charcoal, selenium, polished indigo, and bodies which are not at all metallic. 



2. The metals are excellent conductors of heat, and most of them also of elec- 

 tricity, though probably not all. According to Despretz, they possess the power of 

 conducting heat proportionately to the following numbers: Gold, 1,000; platinum, 

 981 ; silver, 973 ; copper, 898 ; iron, 374; zinc, 363 ; tin, 304 ; lead, 179'6. 



Becquerel gives the following table of metals, as to electrical conduction : 



