The Use of the Blowpipe in Chemical Analysis, and in the Examination of MineralsBaldwin, Cradock, and Joy, and J. Mawe, 1822 - 343 pages |
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alumina analysis antimony arsenic assay atom of bisilicate atom of sulphuret atoms of silicate becomes opaline becomes opaque behaves Berzelius bismuth blast blebby blowpipe borar borax fuses easily brazil wood brazil wood paper carbonate cerium charcoal colourless glass columbite contain copper crystallized cupellation effervescence exterior flame fluoric acid fluxes fumes fuses readily fuses slowly fusible fusion gives off water glass becomes globule grey infusible intumesces Klaproth large quantity lime magnesia malacolite manganese mass matrass odour opaline on cooling opaque on cooling open tube oxidating flame oxide oxide of iron peroxide phosphate phosphorus decomposes platina foil platina wire portion potassa powder protoxide of iron pyroxenes quantity of soda reducing flame roasting salt of phosphorus scoria selenium silica skeleton silicate of alumina silver small quantity soda fuses solution of cobalt species strong heat sublimate substance sulphate sulphurous acid surface tellurium tint transparent glass trisilicate tungstic acid yellow yellowish
Popular passages
Page 56 - REAGENTS, earths, yttria, glucina, zircon, the oxides of cerium, columbiuin, titanium, &c. But one condition of this phenomenon is, that, to a certain point, the glass be saturated with the oxide or the earth. The same thing does not happen with silica, alumina, the oxides of iron, manganese, &c. and the presence of silica is sufficient to prevent the appearance of the phenomenon with those earths which form a glass with borax liable to become opaque, so that it does not ensue at all with their silicates,...
Page 26 - Whenever a flame is remarkably brilliant and dense, it may be always concluded that some solid matter is produced in it: on the contrary, when a flame is extremely feeble and transparent, it may be inferred that no solid matter is formed.
Page 64 - The assay, previously fused with lead, is placed in the middle of the little cupel, and the whole heated by the exterior flame. When the operation is finished, the precious metals are left on the surface of the cupel. This experiment is so delicate, that grains of silver visible to the naked eye, and indeed such as may be collected by the forceps and extended under the hammer, may in this way be extracted from the lead met with in commerce.
Page 24 - ... cylinders ; the air passing through is found very hot, for it will convert paper into charcoal; and it is an explosive mixture, for it will inflame if a lighted taper be presented to it, but it is cooled below the explosive point by passing through wires even red hot, and by being mixed with a considerable quantity of air comparatively cold.
Page 33 - Having moistened the hook with the tongue, it is to be dipped into the flux, a portion of which will adhere to it ; this is to be fused by the lamp into a globule, which congeals and adheres to the curvature : the assay must then be moistened, to make it adhere to the flux, which is now solid, and the whole heated together. We thus obtain an insulated mass, which may be...
Page 29 - A very advantageous mode of practice, in order to acquire the art of making a good reducing flame, is to fuse a small grain of tin, and raise it to a reddish white heat on a piece of charcoal, so that its surface may always retain its metallic brilliancy. Tin has so great a tendency to oxidation, that the moment the flame begins to become an oxidating one, it is converted into an oxide of tin, which covers the metal with an infusible crust. We must begin by operating on a very small grain, and gradually...
Page 6 - Gahn always travelled with his blow-pipe, and the continued use he made of it led him to several improvements in its application ; he examined a great number of re-agents, in order to find new methods of arriving at the knowledge of certain substances, and the whole was imagined and executed with such sagacity and precision, that his results were entitled to the greatest confidence. He most readily and carefully instructed those who were desirous of information on the subject ; but he never appears...
Page 28 - For reduction, a fine beak must be employed, and it must not be inserted too far into the flame of the lamp ; by this means •we obtain a more brilliant flame, the result of an imperfect combustion, whose particles, as yet unconsumed, carry off the oxygen from the subject of experiment, which may be considered as being heated in a species of inflammable gas. If in this operation the assay become covered with soot, it is a proof that the flame is too smoky, which considerably diminishes the effect...
Page 4 - The experience thus acquired enabled Gahn to employ the instrument in every kind of chemical and mineralogical inquiry; and he attained such a degree of skill in its use, that he could detect the presence of substances in a body by its means, which had escaped the most careful analysis, conducted by the ablest chemists of those times. Gahn was indefatigable in his observations and experiments with the Blowpipe, without which he never travelled; and though he was led to contrive several improvements...
Page 2 - ... should produce such modifications on the objects to which they were applied, as might afford some conclusions respecting their composition, and serve as a basis for the classification he adopted. In his time the intercourse between men of science was by no means so open as at present ; the...