{ 37 Hydrate of lime (slaked lime). { 50 Carbonate of lime { (chalk; marble). { 20 MAGNESIA (pure, calcined). { 42 Carbonate of magnesia (dry, { neutral). { 48-1/2 ” ” (ordinary { commercial). { 52 STRONIA (pure, caustic). { 61 Hydrate of strontia. { 74 Carbonate of strontia. =ALKALOID.= _Syn._ VEGETABLE ALKALI, ORGANIC BASE; ALKALOÏDES (_pl._, -IDES, or -IDÆ), L.; ALCALOÏDE, ALCALI ORGANIQUE, Fr. In _chemistry_, a name commonly given to any proximate principle of vegetable origin possessing alkaline or basic properties, however feeble. In its most extended sense the term embraces all organic bases, whether obtained from the animal or vegetable kingdom, or produced artificially. The alkaloids form a numerous and important class of bodies. They exist in nature nearly always in the form of salts, the acid being often, like themselves, peculiar to the plant, or class of plants, in which they are found; whilst the medicinal activity of the latter, in most cases, almost entirely depends on their presence. _Prep._ The following general methods of procuring the alkaloids will be found applicable to such as full directions are not given for under their respective heads:—— 1. (When the base is insoluble in water, non-volatile, and existing in the plant in an insoluble form.) The bruised plant is boiled or macerated in water acidulated with hydrochloric or acetic acid, and the liquor, after filtration, is neutralised with an alkali (ammonia, potassa, lime, or magnesia); the resulting precipitate is purified by re-solution in dilute acid, digestion with a little animal charcoal, and subsequent crystallisation, or re-precipitation with an alkali; or the first precipitate is purified by dissolving it once, or, if necessary, several times, in boiling alcohol, which yields the pure alkaloid either on cooling or by evaporation. 2. (When the base is insoluble in water, and non-volatile, but existing in the plant as a soluble salt.) The bruised or sliced plant is boiled or macerated in water, and the filtered liquor precipitated and otherwise treated as before.