NOBLE METALS. 405 



which we are indebted for our printing. Type-casting is done by hand, and 

 requires much dexterity. A ladle is dipped into the molten metal, and the 

 mould jerked in to fill it properly, and then the type is removed and the 

 mould shut ready for another type ; and a skilful workman can perform 

 these operations five hundred times in an hour, rather more than eight 

 times a minute, producing a type each time ; this has afterwards to be 

 finished off by others. The metal of which type is made consists of lead 

 and antimony ; the antimony hardens it and makes it take a sharper 

 impression. The letters are first cut in steel, and from these "dies " the 

 moulds are made in brass, by stamping, and in these the types are cast. 



Stereotype consists of plates of metal taken, by casting, from a forme 

 of type set up for the purpose : an impression was formerly carried on by 

 plaster-of-Paris moulds, but lately what is termed the papier-mache process 

 is adopted. The paper used is now made in England, and the prepared 

 sheet is placed upon the type and beaten upon it. Paste is then filled in 

 where there are blanks, and another and thicker sheet of the prepared paper 

 is placed over all, dried, and pressed. When this is properly done the paper 

 is hardened, and preserves an impression of the type set up. The paper 

 mould is then put into an iron box, and molten metal run in. In a very 

 short time a " stereotype " plate is prepared from the paper, which can be 

 used again if necessary. The metal plate is put on the machine. 



There are several compounds of antimony, which, though valuable to 

 chemists, would not be very interesting to the majority of readers. We will 

 therefore at once pass to the Noble Metals. 



THE NOBLE METALS. 



There are nine metals which rank under the above denomination : 

 Mercury, Silver, Gold, Platinum, Palladium, Rhodium, Ruthenium, Osmium, 

 Iridium. We will confine ourselves chiefly to the first four on the list. 



MERCURY, or QUICKSILVER, is the first of the metals which remain 

 unaltered by exposure to atmospheric air, and thus are supposed to earn 

 their title of nobility. Mercury is familiar to us in our barometers, etc., and 

 is fluid in ordinary temperatures, though one of the heaviest metals we 

 possess. It is principally obtained from native cinnabar, or sulphide of 

 mercury (vermilion), and the process of extraction is very easy. Mercury 

 was known to the ancients, and is sometimes found native. In the mines 

 the evil effects of the contact with mercury are apparent. 



This metal forms two oxides, the black (mercurous) oxide, or sub- 

 oxide (Hg 2 O), and the red (mercuric) oxide, or red precipitate. The 

 chlorides are two, the subchloride, or calomel, and the perchloride, or 

 corrosive sublimate. The sulphides correspond with the oxides ; the 

 mercuric sulphide has been mentioned. Its crimson colour is apparent in 

 nature, but the Chinese prepare it in a particularly beautiful form. Many 



