3539. To Make Zinc Amalgam for Electrical Machines

3539.     To Make Zinc Amalgam for Electrical Machines. Melt 2 ounces zinc in a ladle, remove from the fire, and stir into it 5 ounces mercury previously heated. Stir till cold, and then powder it. Keep it in a tightly corked bottle.

3540. Improved Electric Amalgam

3540.    Improved Electric Amalgam. It is well known that a deposit of moisture greatly interferes with the action of electrical machines, experiments often wholly failing from this cause, especially in the winter season. Mr. F. Dietlen, of Klagenfurt, has devised a method by which he obviates this difficulty, consisting simply in a modification of the amalgamation of the rubber cushion. For this purpose he pours petroleum over zinc filings, and adds an equal quantity of mercury (though an excess of mercury facilitates the process). The mixture is then brought, by working together in a mortar, to the condition of a homogeneous paste, and pressed between a double cloth. A soft mass is thus obtained, which, however, soon hardens; but which, being finely pulverized and mixed with a proper quantity of grease, is spread upon the rubber cushion. This makes the surface quite glossy, and, when the glass disk has previously been wiped with a piece of cotton slightly impregnated with petroleum or benzine, will develop electricity abundantly, even in damp localities where the usual arrangement fails.

3541. Boettger's Amalgam for Electrical Machines

3541.       Boettger's Amalgam for Electrical Machines. Boettger recommends a mixture of 2 parts (by weight) of pure zinc, while melted, to be mixed with 1 part of mercury. This should be kept in pieces in a well-stoppered flask, and is said to be superior to the amalgam made of 2 parts mercury, 1 zinc, and 1 tin.

3542. Tin Amalgam

3542.     Tin Amalgam. Amalgam of tin forms readily by introducing the solid metal into the mercury. In this way hexagonal crystalline formations have been observed ; there is always a decided contraction in bulk. The hard amalgam of tin obtained by passing the liquid amalgam through fine leather, then drying, and afterwards rubbing under water, forms one of the plastic cements for filling teeth. (See No. 3553 (Alloy for Filling Teeth)). It hardens within a few days, and is, besides, used for hermetically closing glass tubes. Mixed with a little silver amalgam it is a less plastic mass and requires a little more mercury, but it hardens much sooner.

3543. Copper Amalgam

3543.       Copper Amalgam. Copper amalgam is best obtained by first precipitating metallic copper in a fine state of division from a solution of 3 ounces of blue vitriol in a quart of water mixed with an ounce of oil of vitriol, by means of clean wrought iron; then, after washing it thoroughly with hot water, moistening the powder with a solution of proto-nitrate of mercury, and finally incorporating it under water in a mortar with the required quantity of mercury. This amalgam, like the hard amalgam of tin, has the property of being softened and rendered plastic by mere trituration with a pestle. The proportions are generally 3 parts of copper to 7 of mercury.