Scenes of commerce, by land and sea, or, "Where does it come from?" answered / upon a plan arranged by the Rev. Isaac Taylor.

  • Isaac Taylor
Date:
1839
Catalogue details

Licence: Public Domain Mark

Credit: Scenes of commerce, by land and sea, or, "Where does it come from?" answered / upon a plan arranged by the Rev. Isaac Taylor. Source: Wellcome Collection.

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    PEARLS. 263 equal in that respect to many of the coloured stones, and even superior to some of them. To give an emerald colour, brass, thrice calcined, is added ; for a sea-green, brass simply calcined to redness ; for sapphire, the additions are, zaffer and manganese ; which are also used in different proportions for ame¬ thyst ; for topaz, manganese and tartar. A very fine red is made from gold ; and one, not much inferior, from iron. A sky colour As obtained from silver ; and much finer from Bohemian granite. Other com¬ positions are used for the different colours which you see in jewellery of this kind ; some resembling the natural gems, and others dictated by fancy. 44 When the paste has been formed at the glass¬ house, it is sent to the lapidary, who cuts and po¬ lishes it to the required pattern ; and then the jew¬ eller performs his part of setting the stones in gold, or inferior metal. 44 The composition which I have described, is the hardest and best; but in many cases, other mate¬ rials are used, which require less attention, and are much cheaper ; at the same time they are much softer, and more generally used for coloured stones. The most simple of these is : six parts of white sand, cleansed ; three parts of red lead ; two parts of pu¬ rified pearl-ash ; and one part of nitre. These, poun¬ ded, mixed, and calcined, make a paste fit for ear¬ rings, brooches, and such articles as are not liable to be much rubbed; but it is unfit for rings, buckles, or whatever may be exposed to scratches. PEARLS. 44 We now proceed to pearls, which, as I have already hinted, are procured from shell-fish of the oyster and muscle kind; and are in fact drops of
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