MacKenzie's five thousand receipts in all the useful and domestic arts : constituting a complete practical library ... : a new American, from the latest London edition : with numerous and important additions generally : and the medical part carefully revised and adapted to the climate of the U. States : and also a new and most copious index / by an American physician.

  • Mackenzie, Colin, 1775?-1827.
Date:
[1829]
Catalogue details

Licence: Public Domain Mark

Credit: MacKenzie's five thousand receipts in all the useful and domestic arts : constituting a complete practical library ... : a new American, from the latest London edition : with numerous and important additions generally : and the medical part carefully revised and adapted to the climate of the U. States : and also a new and most copious index / by an American physician. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

    13/464
    dwt. gr. dwt.gr. Requires from f 11 6 to 5 to 6~J ri 0 12 to 8 to 9 I m S B 19 18 to 9 0 12 to 13 -C p j 8 6 to 7 12 13 to 14 >£ ° '*t 6 18 to 6 0 14 to 15 £ - 3 0 to 1 12 Oto 16 H-f I 12 to 0 18 0 to 20 * ny-weights; 3 real grains represent 1 fine penny- weight, or 24 grains; a real grain and a half repre- sent 12 fine grains; l-32d of a real grain represents a quarter of a fine grain, which is only 1-752*1 part of a mass of 12 penny-weights. Double assay of silver. It is customary to make a double assay. The silver for the assay should be taken from opposite sides of the ingot, and tried on a touch stone. As- sayers know prett; nearly the value of silver merely by the look of the ingot, and still better by the test of the touch stone. The quantity of lead to be added is regulated by the portion of alloy, which being in general copper, will be nearly as follows: Of silver wt. gr. d\ 11 6 to 0 12 to 19 18 to 8 6 to 6 18 to 3 0 to 1 12 to The cupel must be heated red hot for half an hour before any metal is put upon it, by which all moisture is expelled. When the cupel is almost white by heat, the lead is put into it, and the fire increased till the lead becomes red hot, smoking, and agitated by a motion of all its parts, called its circulation. Then the silver is to be put on the cupel, and the fire continued till the silver has en- tered the lead; and when the mass circulate? well, the heat must oe diminished by closing more or less the door of the assay furnace. The heat should be so regulated, that the metal on its surface may appear convex and ardent, while the cupei is less red; that the smoke shall rise to the roof of the muffle; that undulations shall be made in all direc- tions; and that the middle of the metal shall a\ pear smooth, with a small circle of litharge, which is continually imbibed by the cupel. By this treat- ment the lead and alloy will be entirely aosorbed by the cupel, and the silver become bright and shining, when it is said to lighten; after which, if the operation has been well performed, the silver will be covered with rainbow colours, which quick- ly undulate and cross each other, and then the but- ton becomes fixed and solid. The diminution of weight shows the quantity of alloy. As all lead contains a small portion oi sil- ver, an equal weight with that used in the assay is tested off, and the product deducted from the assay- weight. This portion is called the witxess.—Ri- chardson's Metallic Jirts. Ores and earths containing gold. That which is now most generally used is by amalgamation, the proper quantity is taken and reduced to a powder; abo'H one-tenth of its weight of pure quicksilver is added, and the whole tritu- rated in an iron mortar. The attraction subsisting between the gold and quicksilver, quickly unites them in the form of an amalgam, which is pressed through shumoy leather; the gold is easily sepa- rated from this amalgam, by exposure to a proper degree of heat, which evaporates the quicksilver, and leave!, the gold. This evaporation should be made with luted vessels. This is the foundation of all the operations by which gold is obtained from the rich mines of Peru, in Spanish America. Another method.—Take a quantity of the gold sand and heat it red hot, quench it in water; repeat this two or three times, and the colour of th.J sand will become a reddish blown. Then mix it with twice its weight of litharge, and revive the litharge into lead, by adding a small portion of charcoul- dust, and exposing it to a proper degree of heat; a wheU the lead revives, it separates the gold from the sand; and the freeing of the gold from the lead must be afterwards performed by cupellation. Another.—Bergmann assayed metallic ores con- taining gold, by mixing two parts of the ore well pounded and washed, with 1 and a \ of litharge, and 3 of glasj; covering the whole with common talt, and melting it in a smith's forge, in a covered crucible; he then opened the crucible, put a nail into it, and continued to do so till the iron was no longer attacked. The lead was thus precipitated * which contained the gold, and was afterwards sepa- rated by cupellatiun. Humid assay of gold mixed -with martial pyrites. Dissolve the ore in 12 times its weight of dilute nitrous acid, gradually added; place it in a proper degree of heat; this takes up the soluble parts, and leaves the gold untouched, with the insoluble ma- trix, from which it may be separated by aqua regia. The gold may be again separated from the aqua regia by pouring ether upon it; the ether takes up the gold, and by being burnt off leaves it in its me- tallic state. The solution may contain iron, cop- per, manganese, calcareous earth, or argil; if it be evaporated to dryness, and the residuum heated to redness for half an hour, volatile alkali will extract the copper; dephlogisticated nitrous acid the earths; the acetous acid the manganese; and the marine acid the calx of iron. The sulphur floats on the first solution, from which it should be separated by filtration. ALLOYS OR COMPOUND METALS. Metals, in general, will unite with each other by fusion or amalgamation, and acquire new proper- ties. Brass is a compound of copper and zinc; and possesses a different colour to either of the com- ponent parts. The attraction of cohesion of the different me- tals which are to form the compound must be over- come; accordingly, they become intimately mixed together. The compound is not formed by a che- mical union of the particles of the different metals, but from an equable diffusion throughout each other, in mass. As metals fuse in different de- grees of heat, care should be taken not to acid those metals which fuse easily, to others which require a greater degree of heal, while they are too hot; because the former may evaporate and leave the compound imperfect. Or, if they are'brqught intc fusion together, it should be under u tlux to pre\ en) the volatile metals from evaporating, before the union is effected. O' inolu—Mosaic gold. Melt together equal parts oi copper and zinc. at the lowest temperature that tuillfuse the former; stir them well to produce an intimate mixture of the metals, and add by degrees small quantitiesof zinc; the alloy first assumes a yellow colour like brass, on adding a- little more zinc .t becoinospur- ple, and lastly perfectly white, Which is the propel appearance of the desired product, when fused. The quantity of zinc to he used altogether, should be from fifty-two to fifty-five parts out of a hun- dred. Queen's metal Melt together A$ lb. of tin, h lb. of bismuth, \ lb. of antimony, and £ lb. of lead. A very excel- lent alloy will be formed by using these propor- tions; it is used for making tea-pots and other ves- sels which are required to imitate silver. They retain their brilliancy to the last. Another.—A very fine silver-looking metal is composed of 1U0 pounds of tin, 8 of regains of an- timony, 1 of oismuth, and 4 ol copper.