Lime is also sometimes employed as a mordant, but it does not answer so well in general, not giving so good a colour. It is used either in acetate of lime water, or as a sulphate of lime dissolved in water. A solution of indigo in the sulphuric acid is used for dyeing wool. This is called the _Saxon blue_, and it gives a very beautiful colour. To dye by the sulphate of indigo, dissolve one part of indigo in four parts of concentrated sulphuric acid; add to the solution one part of dry carbonate of potash, and dilute the whole with eight times its weight of water. Boil the wool for an hour in a solution of five parts of alum, and three of tartar, for every thirty-two parts of cloth. The wool is then to be put in a bath of sulphate of indigo, diluted according to the strength of shade required, and kept till it has acquired the desired colour. The use of the alum and tartar is not to act as mordants, but to facilitate the decomposition of the indigo; and the alkali is added to the sulphate for the same reason. ACID, _a._ Sour, sharp. ACIDS, _s._ In veterinary practice are divided into three classes, mineral, vegetable, and animal. _Mineral_ are sulphuric, nitric, and muriatic. _Vegetable_, acetic (vinegar), and tartaric (cream of tartar). Muriatic acid is commonly called spirit of salt. Sulphuric, oil of vitriol. ACTION, _s._ The accordance of the motions of the body with the words spoken. In _sporting parlance_, it is used to describe the movements of a horse. ADDER, _s._ A serpent, a viper, a poisonous reptile. Adders or vipers are found in many parts of Europe; but the dry, stony, and in particular the chalky countries abound with them. These animals seldom grow to a greater length than two feet; though sometimes they are found above three. The ground colour of their bellies is a dirty yellow; that of the female is deeper. The whole length of the back is marked with a series of rhomboid black spots, touching each other at the points; the sides with triangular ones; the belly entirely black. It is chiefly distinguished from the common ringed snake by the colour, which in the latter is more beautifully mottled, as well as by the head, which is thicker than the body; but particularly by the tail, which, in the viper, though it ends in a point, does not run tapering off to so great a length as in the other. When, therefore, other distinctions fail, the difference of the tail can be discerned at a single glance. The adder differs from most other serpents in being much slower, as also in excluding its young completely formed, and bringing them forth alive. The kindness of Providence seems to be exerted not only in diminishing the speed, but also the fertility, of this dangerous creature.