Prepared in this way, quinine forms a white amorphous mass. It is inodorous, very bitter, soluble in about 350 parts of cold water, and 400 parts of boiling water, iu 2 parts of cold alcohol, 60 parts of ether, and 6 parts of chloroform. Quinine is a powerful alkali; it alters vegetable colours, and forms a series of well-defined stable salts, among which is a soluble carbonate. Sul phate of quinine is much valued as a medicine, and as it is very expensive, it is much adulterated. The principal adulterations are crystallized sulphate of lime, boric acid, auger, salicine, me naite, atearic acid, and the sulphates of cinchonine, and quinidine. Imperfect purification, however, will often account for the presence of the two latter.
Strychnine.—Strychnino is contained in the Strychnos nux cornice and in the St. Ignatius bean. The method of preparing it has boon described under Bruciue.
Strychnine is colourless and inedorous, but has an extremely bitter taste. It dissolves in 6667 parts of cold water, and in 2500 parts of boiling water. It is a most deadly poison, half a grain being sometimes sufficient to cause death, though its effects vary with different individuals. It is much valued as a medicine for paralytic disorders, but the utmost care should be taken in the use of it, for very many deaths have been caused through carelessness in adminis tering too large doses of this dangerous remedy. It was formerly largely made use of for the purposes of the poisoner, but chemical science has rendered the detection of it so easy and so certain that it has happily been abandoned of late years. It is an ingredient in various poisons for vermin, beetles, &c., though it is not by any means to be recommended for this purpose.
Alkaline Earths.—The term "alkali" formerly comprehended only the four substances, potash, soda, ammonia, and litbia. It has new, however, come to be used in a much wider sense, comprising a very large number of bodies possessing similar properties to the four above mentioned. Among these are the metallic oxides, baryta, lime, and strontia, to which were given the name of the "alkaline earths," probably to distinguish them from certain other earths, not possessing the properties of an alkali, such as alumina and magnesia. The distinguishing characteristics of the alkalies are their solubility in water ; their power of neutralizing acid; the corrosive action exerted by their aqueous solutions all animal and vegetable matter ; and the property of changing the colour of vegetable colouring matter, such as litmus and turmeric. All
these conditions are fulfilled to a greater or less extent by the alkaline earths ; the only point of difference seems to be that their carbonates are insoluble, or almost insoluble in water : whereas the carbonates of the alkalies proper are very freely soluble therein.
Baryta, BaO. This earth may be prepared by the ignition of the nitrate or carbonate of barium. When required in quantity the best method consists in heating in a porcelain retort a mixture of nitrate and sulphate of barium, the weight of the latter being slightly in excess. If the nitrate be heated alone, it fuses and is apt to attack the porcelain. A strong red heat is required. Baryta is also prepared by heating the carbonate with one-tenth of its weight of lampblack; the mixture is made into a paste with oil, and subjected to a white heat, in a porcelain or earthenware crucible.
Baryta is extremely caustic, poisonous, and strongly alkaline. It is infusible, except in the oxyhydrogen blow-pipe flame. It unites readily with water, forming the hydrate BaHO. It is soluble in ten parts of boiling water ; this solution is used in the laboratory as a test for sulphuric acid. Baryta is also used in sugar-refining (see Sugar).
Lime, CaO. When carbonate of lime is strongly heated, it decomposes, forming lime and car bonic acid gas. This process is conducted on a very large scale, and is called " lime-burning " (see Lime). Lime does not exist naturally, but, in combination with carbonic acid, it constitutes a considerable portion of the earth's crust. It is a bard, white powder. It is absolutely unaltered by the highest known temperatures. It absorbs water eagerly, giving out much heat and forming the hydrate or " slaked " lime, CaHO. The applications of this substance to the arts and manufactures are exceedingly numerous, and will be considered under the article on Lime.
Strontia, SrO.—Strontia does not occur naturally, but it may be prepared by igniting either the carbonate, strontiauite, which is found in the lead mines of Strontian, in Argyllshire, or the sulphate, celestine. It is of a greyish-white colour, infusible except the oxyhydrogen blow pipe flame, and has a strongly alkaline reaction. It combines readily with water, giving out heat and passing to the hydrate, SrHO, a fine white powder. The salts of strontium are extensively used in pyrotechny for the preparation of "red fire" (see Pyrotechny).