The blowpipe vade macum : the blowpipe characters of minerals deduced from the original observations of Aquilla Smith ; alphabetically arranged and edited by Samuel Haughton and Robert H. Scott / [Aquilla Smith].

  • Smith, Aquilla, 1806-1890.
Date:
1862
Catalogue details

Licence: Public Domain Mark

Credit: The blowpipe vade macum : the blowpipe characters of minerals deduced from the original observations of Aquilla Smith ; alphabetically arranged and edited by Samuel Haughton and Robert H. Scott / [Aquilla Smith]. Source: Wellcome Collection.

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    Platinum Forceps One of the greatest advantages of this instru- ment is, that it enables us to fix the object of experiment in a steady position; and by this means a very minute fragment, which it would be impossible to keep fixed on charcoal, can be examined with great ad- vantage. The cliief advantage of this instrument is that it enables the operator to submit a mere fragment of a mineral to a high and uniform tempe- rature, which could not be etfected on charcoal, as the assay would be blown away the moment the jet iron the pipe would be directed on it. Hence we have found several minerals which on charcoal were appa- rently infusible, yet when placed in the forceps, and submitted to a well- directed fiame, fuse without difficulty on the edge; and besides it-enables us to observe the effect of the assay on the fiame, in producing certain colours which are very characteristic of some minerals, as Carbonate of Strontia andLepidolite, which tinge the flame red; Cyprine and Boracite, which impai-t a green colour. The forceps may be used with advantage in the examination of all the earthy and many of the metallic minerals, particularly such as are refractory on charcoal. We should, however, be cai’eful not to employ it as a support for those metallic oxides and compounds which are reducible per se before the Blowpipe, and readily form an alloy Avith platina. The forceps are used for holding a small portion of a mineral, when we wish to try its fusibility. The most convenient form of this instru- ment consists of two thin plates of steel, each having apiece of flattened platina about the sixteenth of an inch wide riveted on its extremitj'. The platina points should possess as little bulk as possible, in order that little heat may be abstracted. These plates are fastened m the middle to a small piece of iron or brass, somcAvhat of wedge-shape, so that the pla- tina extremities are held in close apposition by the spring of the steel plates, while the other extremities are separated about a quarter of ;m inch, and may be nsed as an ordinary spring forceps. The platina ex- tremities are opened by pressing the fore-finger and thumb against two small buttons, the shanlc of each of which is fixed in one plate, and passes through the other. VI. Additional Instruments. Under this head we arrange all those instniments which are used for various purposes, subservient to the examination of minerals. ^ 1. The Common Steel Cutting Pliers—Is very useful for detaching small portions from a specimen, Avithout the risk ot injuring it by the concussion which Avould be caused by a hammer.^ 2. A small Jeweller''s Hammer—Is also uselul for detaching frag- ments for examination from specimens, and for ascertaining the mallea- bility of the globules obtained from metaUic minerals. _ 3. A small Anvil—Ifi used for crushing pieces of minerals, Avliich are to be AA^rapped in paper, in order to prevent the dispersion of the frao-ments, and also for trying the malleability of metals. We have pre-