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LEFT SOAP 473 SOCIAL HYGIENE strength are acquired, and the nicotine and organic acids removed. The con- sumption of snuff in the British Isles has been estimated to amount to BOO tons annually. The practice of snuff taking was introduced from America into France in the 16th century, and in the middle of the following century it was very general throughout Europe. The consumption of snuff greatly increased in England during the reigns of William and Anne, and snuff-boxes of gold, silver, precious stones, and enamels were then not uncom- mon. An average of about i/,000 tons are annually made in the United States, consumed principally by foreigners. SOAP, strictly speaking, a salt con- sisting of a fatty acid in combination with a metallic base. In common par- lance, however, the term is applied to the soluble salts formed by the union of the fatty acids with the alkalies. If oil and water be shaken together mechanical union will take place; but on allowing the mixture to rest, the oil will gradually separate and float on the surface of the water. If a small quantity of caustic soda or potash be added to the mixture, and it be then agitated, union will take place between the three bodies, a milky fluid being formed. If a sufficient quan- tity of alkali has been added, and the solution be boiled, it gradually becomes clear, giving rise to a soapy fluid, which froths strongly on agitation, presenting all the properties of a solution of soap. If to a portion of this clear liquid a strong solution of common salt is added, a peculiar curdling is produced. The liquid separates into a clear fluid, con- taining glycerin, while the curdy portion rises to the surface. This substance is the fatty acid of the oil, in combination with the alkali used and a certain proportion of water, and if pressed and dried, ex- hibits the properties of ordinary soap. Ordinary soaps are of two kinds, — soft and hard. Soft soap is a combination of some fatty or oily substance with potash, and contains an excess of alkali; hence it is used for cleansing purposes where very highly detergent powers are re- quired. The hard soaps are combinations of the fatty acids with soda ; the principal varieties being yellow soap, made from tallow and palm oil, and containing a certain proportion of resin to give it lathering properties; curd soap, which is made from tallow, only a small portion of olive oil or lard being added, to give it softness; mottled soap, which is pre- pared from tallow, palm oil, and kitchen stuff, and contains a portion of insoluble iron soap giving it a marbled appearance. Marseilles and Castile soaps are made of olive oil and soda, a small quantity of sulphate of iron and sulphuretted lye being added to them while in a pasty con- dition. The object of marbling soap with an insoluble matter is to show that they contain but little moisture, since, if too large a proportion of water were present, the coloring matter would sink to the bottom and remain there, instead of be- ing diffused through the mass. The United States stands at the head of all other countries in the use if not in the manufacture of soap. New York, Illinois, New Jersey, Ohio and Pennsyl- vania lead, in the order named, all other states. Over 2 billion pounds of hard soap (including about 170,000,000 pounds of toilet-soap) are annually produced and 57,000,000 pounds of soft soap. SOAPSTONE, or STEATITE, a hydra- ted silicate of magnesia. It is a massive variety of talc, which, when pure and compact, is much used as a refractory material for lining furnaces. It is easily turned in the lathe, or cut with knives' and saws, and is made into culinary ves- sels. When reduced to powder it is used like plumbago as a lubricator and to diminish friction. Soapstone slabs are extensively used for manufacturing into laundry, bath and acid tubs, and in chemical labora- tories, as also in the manufacture of dif- ferent varieties of stoves, mantels, linings, heaters, caskets, assay furnaces, gas burners, and wherever acids are used or there is a necessity to retain heat, or where a fireproof article is necessary. See Talc. SOAR, a river of England, which flows N. through Leicestershire, taking Leices- ter on its course, and joins the Trent about 12 miles E. S. E. of Derby, whence to Leicester it is navigable by barges. SOBRANJE, the national assembly of Bulgaria (q. v.). SOCIAL CONTRACT, or ORIGINAL CONTRACT, that imaginary bond of union which keeps mankind together, and which consists in a sense of mutual weak- ness and dependence. Jean Jacques Rous- seau maintained that the natural and proper state of man is the savage state, when he possesses complete liberty, and that every social organization is an in- fraction of natural right. All men he be- lieved are born equal, and society is founded on a social contract. His views on the subject prepared the way for the first French Revolution. SOCIAL, or PUBLIC, HYGIENE, the science of caring for the physical well- being of entire communities, as simple hygiene is the science of guarding the physical welfare of the individual against