MERCAPTANS (Latin, staking up cury') or THIO-ALCOHOLS, iri cherniim a large class of substances having the snit constitution as the alcohols, but differing froze them by having the oxygen atom in the by droxyl replaced by sulphur. They are oily liquids or crystalline solids having an offensive, flic-like odor, and are all insoluble in Water. possess acid tendencies that are mon marked than those of the alcohols, and bine with metallic oxides to form salts which are known as They confine with especial facility with mercuric oxide their name from this circumstance. Ethyl mercaptan is the best-known members of the series, and it is this substance that is under stood when umercaptans is spoken of, without further qualification. Ethyl CIHa.SH, is prepared by acting upon ethyl chloride, C21-11CL, with potassium hydrosulphide, HKS; the potassium atom and the ethyl radi cal changing places as indicated by the equa tion C:1-15C1+ HKS=GH,SH-F Ka. Ethyl mercaptan is a colorless, mobile liquid, boilin at 99° F. It is very inflammable, a blue flame, and it mixes readily with a I and ether, though only to a very slight extent with water. Like the other enercaptans, it forms salts with the oxides of the metals, the hydrogen atom that is associated with the se. phur being the one that is replaced by the metal. The mercury salt, Hg(S. C.}1.)., may be prepared very readily by agitating the met captan (or its alcoholic solution) with red oxide of mercury, HgO. Its formation is at tended by the liberation of considerable quasi dties of heat, and the mercaptide itself is ob tained in the form of soapy white scales. Al of the metallic mercaptides are decomposed by hydrochloric acid. The mercaptans of fatty
radicals all give a fine green color when treated with a solution of isatin in strong phuric acid and this reaction (as well as their insufferable smell) is used as a test for their presence.
MERCATOR,
Oerardus (Lat inized form of GERHARD Karam), Flemish mathematician and geographer: b. Rupelmonde, Flanders, 5 March 1512; d. Duisburg, 2 Dec. 1594. He studied at Louvain, and became a lecturer on geography and astronomy, making his instruments with his own hands. In 1544 he was arrested for heresy, being liberal in his views. He escaped, but 42 of those arrested with him were burnt alive. Recommended to Charles V, Mercator entered into the emper or's service, and executed for him a celestial globe of crystal, and a terrestrial globe of wood. In 1559 he retired to Duisburg and re ceived the title of cosmographer to the Duke of Juliers. His last years were devoted to theological studies. He is known as the in ventor of a method of projection called by his name, in which meridians and parallels of lati tude cut each other at right angles, and are both represented by straight lines, which has the effect of enlarging the degrees of latitude as they recede from the equator. The method is convenient in mapping'small areas. His first maps on this projection
published in 1569; the principles were first explained In Edward Wright, in 1599, in his