Page:The American Cyclopædia (1879) Volume I.djvu/399

AMALGAMATION AMALIE 375 is found to be itself an amalgam, containing a smaller proportion of the harder metals, seem- ing to indicate two definite compounds of dif- ferent proportions. This is observed with the amalgam of mercury with silver, and also with tin. In tinning mirrors, the glass plates are laid upon smooth stone tables covered with the amalgam. The solid portions adhere in a thin film to the glass ; and this is a compound of atomic proportions. The liquid squeezed out by the weight placed upon the glass proves also to be an amalgam containing but a small proportion of tin. Amalgams are prepared by putting the harder metals, reduced to small size, in mercury, and dissolving them with or without heat, as may be required. When the metals are not easily dissolved, they may be rubbed together or triturated in a mortar, or melted, and the mercury heated and poured into the fused metal. This is the process for preparing an amalgam of 4 parts mercury, 2 zinc, and 1 part tin, for the electrical machine. The zinc is first melted, the tin added, and then the hot mercury stirred in. It is to be shaken till cold, then triturated and sifted in a fine sieve. An amalgam of mercury with iron is prepared by rubbing together in a mortar clean iron filings and zinc amalgam, and adding a solution of perchloride of iron. By rubbing and heating this mixture a bright amalgam of iron and mercury is produced. Some amalgams take a crystalline form, thus indicating combination in definite proportions ; and there is also a native amalgam of this character of mercury with silver. This is found in dodecahedral crystals, consisting of 1 atom of silver and 2 of mercury =36 per cent, of the one and 64 of the other. One part of gold heated with 6 parts of mercury crystal- Uzes on cooling in four-sided prisms. Tin amalgam made of 3 parts of mercury and 1 of tin forms cubic crystals. Amalgams freed from their excess of mercury are, when freshly made, dry pasty substances, which soon become hard like stone. This property makes some of them convenient for filling cavities of teeth, but the injury the mercury may effect upon the system renders their use highly objectionable. AMALGAMATION, the process of extracting gold and silver from the gangues in which they occur in nature by combining them with mer- cury. The ores are crushed and then washed through different machines in which mercury is placed. This seizes upon the little particles of the metals that come in contact with it, and brings them together into one mass, from which the earthy matters are all washed away. Any greasy substance present almost wholly prevents this effect, the grease adhering in a film upon the surface of the mercury, and thus rendering impracticable the close contact ne- cessary for their union. The amalgam is from time to time taken out of the washing machines, squeezed through cloth or dressed deerskin, the liquid portion replaced, and the solid distilled in an apparatus suitable for saving the mer- cury, which is then ready for use upon another lot of ore. The silver residue from distillation needs refining to render it perfectly pure. There are two processes for separating silver from its ores by amalgamation the European process in barrels, and the American in heaps. The ore is treated in the European process by pulverizing the ore and roasting it with an ad- mixture of common salt ; by this means all the silver, which was originally a sulphide, is con- verted into the chloride. The roasted ore is then placed in barrels which can be revolved upon a vertical axis, and is thoroughly loosened and stirred up with water. Iron in the form of nails or scrap is then added, which takes the chlorine from the silver and yields the latter in the metallic state. Mercury is then added in larger quantity than is sufficient to amalgamate all the silver. After the barrel has revolved for an hour or more the mercury will have ta- ken up the silver, and is then drawn off. This mercury is filtered and distilled as above de- scribed. The American process of amalgama- tion in heaps has the advantage of simplicity, and although not so perfect in its extraction of silver, it does not require fuel and expensive apparatus. The ore is first broken up to the size of a pea by means of rude stamps, and then ground to fine powder in round cylindrical tubs with bottoms of stone. Each tub has a horizontal arm revolving with its centre upon the vertical axis of the tub, and having at each end a chain attached to a stone weighing from 50 to 100 pounds. When the arm is revolved, these stones are dragged round and pulverize the ore. The ore is then placed on an amalga- mating floor built of stone, and is mixed with a little salt and mercury. After some days the mercury is collected, filtered, and distilled as above described, to save the silver. AMALIA, Anna, duchess of Saxe-Weimar, sec- ond daughter of Duke Charles of Brunswick- Wolfenbiittel, born Oct. 24, 1739, died April 10, 1807. She was married to Duke Ernest of Weimar in 1756. After her husband's death in 1758 she took the reins of government, and held them so well that Saxe-Weimar was able speedily to recover from the effects of the seven years' war, and escaped the famine of 1773. In 1775 she resigned the administration to her son, and devoted herself to the cultivation of literature. For 30 years she lived in the soci- ety of Wieland, Goethe, Herder, Schiller, and other men of eminence. AMALIE, Marie Friederike, queen of Greece, born Dec. 21, 1818. She is a daughter of the late grand duke Paul, and half sister of the reigning grand duke Nicholas. of Oldenburg, and was married to King Otho of Greece Nov. 22, 1836. She imparted a high tone to the court circles of Athens, and was much respected in Greece on account of her firmness, her be- nevolence, and her varied accomplishments, In 1856 she acted as regent during the foreign occupation of Athens. A Greek student made an attempt to shoot her in 1861. On Oct. 24,