Page:The American Cyclopædia (1879) Volume I.djvu/346

 322 ALKALI ALKMAAR which, when perfectly washed and dried, is artificial alizarine. The artificial product ap- pears to be entirely identical with the coloring matter obtained from the madder root. Both the natural and the artificial products crystal- lize in needles and dissolve in caustic alkalies, forming violet solutions of the same tint and possessing precisely the same tinctorial value. Applied to mordanted fabrics, they produce exactly the same colors, and they resist equally well the action of light. If an adequate sup- ply of anthracene can be obtained, the artificial production of alizarine bids fair to become an established industry of great importance. ALKALI (Arabic, al-qali, the ashes of the plant glasswort, yielding soda), the general name of a class of substances, such as caosia, rubidia, potash, soda, lithia, and ammonia, whose distinguishing peculiarities are solubility in alcohol and water, uniting with oils and fats to form soap, neutralizing and forming salts with acids, reddening several vegetable yellows, and changing reddened litmus to blue. These properties are the reverse of those of acids, and the two classes are regarded as an- tagonistic to each other. Some other sub- stances, as lime, baryta, strontia, and magne- sia, possessing some of the qualities of the alkalies as neutralizing acids, and changing the vegetable colors, are called alkaline earths. Pure anhydrous alkalies are exceedingly caus- tic, destroying vegetable and animal tissues. They abstract moisture rapidly on exposure to the air. Combined with carbonic acid and water, forming carbonates, they are used in medicine as diuretics and for correcting acidity, as well as for other effects. The alkalies and the earths also were until the present century regafded as simple substances. Lavoisier first suggested that they were metallic oxides. Sir Humphry Davy proved this in 1807, by sepa- rating the metals, to which he gave the names potassium, sodium, barium, strontium, and cal- cium, the last the metallic base of lime. The discovery of these metals led to that of pure potash and soda. The alkalies were known before only in the state of hydrates, though incorrectly regarded as anhydrous. ALKALIMETRY, the process employed to esti- mate the quantity of alkali present in any mix- ture. Its principle consists in exactly neutral- izing a certain weight of the alkali, and know- ing the quantity of acid of a given strength which is required to effect this. The alkaline substance, carefully weighed, is dissolved in warm water, placed in an alkalimeter, which is usually a graduated glass tube, and diluted sulphuric acid cautiously and slowly added till the solution is made neutral. This is known by the use of little bits of test paper in the liquid, which, by their change of color, indicate the slightest acid or alkaline reaction. The process may be reversed to test the strength of acids, and is then called acidimetry. ALKALOID, vegetable alkali, a name given to vegetable extracts possessing the property of uniting with acids to form salts in the same manner as ammonia. The first alkaloid was discovered by Serturner in 1804 in opium; bui little importance was attached to the announce- ment, and it was not till 1817 that the real value of morphine was demonstrated and the existence of vegetable alkalies fully shown. Since that time the list of alkaloids has rapidly increased, until at the present time (1872) they number more than 100. There are two classes, volatile liquids and permanent solids. The former contain simply carbon, hydrogen, and nitrogen, and only three of them are known, coniine, nicotine, and sparteine. The solid and most numerous alkaloids contain carbon, hydrogen, nitrogen, and oxygen. The organic bases are colorless and generally crystalline. They are insoluble or slightly soluble in water, the best solvent being alcohol. Ether dissolves some of them ; chloroform and the hydrocar- bons are also good solvents. They generally possess powerful medicinal properties. Nu- merous artificial alkaloids have been formed, the most important of which is aniline. The natural base coniine has also been made artifi- cially. Some of the best known of the vegetable alkaloids are nicotine, quinia, morphia, strych- nia, brucia, aconitina, atropia, and caffeine. ALKANA. See HENNA. ALKANET, the commercial name of two differ- ent plants. True alkanet consists of the roots and leaves of the Lawsonia inermis, which grows wild in the Levant. The leaves pulverized and made into a paste yield a yellow dye. The root, which contains a red pigment, is used as a cosmetic. False alkanet (orcanette, radix alcanna spuria) is the root of anchusa tincto- ria, which grows in France, Spain, Italy, Hun- gary, and Greece. It is inodorous, has a faint, somewhat astringent taste, and colors the saliva. It is used in dyeing goods previously prepared with alum mordants for violet, and iron mordants for gray. The mordanted linen or cotton goods are dipped in an alcoholic ex- tract of the root. It is also used for dyeing silk, but not wool. The coloring matter is called anchusine. The violet and gray colors are brilliant. ALKINDI, or Aldiindus, an Arabian physician and philosopher, born in Bassorah at the end of the 8th century, died in the middle of the 9th. Some, however, place his life two or three centuries later. He wrote more than 200 different treatises on logic, music, ge- ometry, arithmetic, astronomy, medicine, &c. His treatise known under the Latin title De Theoria Magicarum Artium has secured for him the fame of a magician. Various other works of his were translated into Latin during the middle ages, and published at Paris, Stras- burg, and Venice. His theories are distin- guished by great ingenuity, so much so that Cardan ranked him among the twelve subtle spirits of the world. ALKMAAR, a well built and strongly fortified town of the Netherlands, in North Holland, on