1911 Encyclopædia Britannica/Paste

PASTE (O. Fr. paste, modern pâte. Late Lat. pasta, whence also in Span., Port, and Ital., from Gr. πάστη or παστά, barley porridge, or salted pottage, πάσσειν, to sprinkle with salt), a mixture or composition of a soft plastic consistency. The term is applied to substances used for various purposes, as e.g. in cookery, a mixture of flour and water with lard, butter or suet, for making pies and pastry, or of flour and water boiled, to which starch or other ingredients to prevent souring are added, forming an adhesive for the affixing of wall-paper, bill-posting and other purposes. In technical language, the term is also applied to the prepared clay which forms the body in the manufacture of pottery and porcelain (see Ceramics) and to the specially prepared glass, known also as “strass,” from which imitation gems are manufactured. This latter must be the purest, most transparent and most highly refractive glass that can be prepared. These qualities are comprised in the highest degree in a flint glass of unusual density from the large percentage of lead it contains. Among various mixtures regarded as suitable for strass the following is an example: powdered quartz 300 parts, red lead 470, potash (purified by alcohol) 163, borax 22, and white arsenic 1 part by weight. Special precautions are taken in the melting. The finished colourless glass is used for imitation diamonds; and when employed to imitate coloured precious stones the strass is melted up with various metallic oxides. Imitation gems are easily distinguished from real stones by their inferior hardness and by chemical tests; they may generally be detected by the comparatively warm sensation they communicate to the tongue.