Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 4, 1802).djvu/422

388] , has published several volumes ou the culture and useful properties of the Acacia.  ACIDS.—The citric acid is a concrete juice obtained principally from : it has also been discovered in the red whortleberry, cranberry, bird-cherry, as well as in the fruits of the woody nightshade, and the dog-rose.

In order to divest this acid of the mucilaginous or other foreign particles, with which it is frequently combined, the juice obtained by pressure from lemons, or similar fruit, should first be heated, then strained, filtred, and afterwards saturated with pulverized chalk, or the carbonate of lime, till all effervescence cease. The precipitate, formed by this process, is called citrate of lime; and, being insoluble, it must be separated from the liquor, washed with cold water till it become tasteless and perfectly white: next, it ought to be decomposed in a gentle heat, by adding half its weight of sulphuric acid diluted with six parts of water. As soon as the mixture becomes cool, it should be filtred; when the pure citric acid will be disengaged from the sulphate of lime.—Such acid may also be obtained in a crystalline form, by previously filtering, and then evaporating it to the consistence of a clear syrup, which concretes on exposing it to a cold temperature.

Dr. has lately published a new method of preserving and concentrating the acid of lemons. He directs the newly expressed juice to be strained through fine linen, a small portion of rectified spirit of wine to be added, and the whole to be deposited for several days in a bottle closely stopped: thus, a considerable mucilaginous sediment will be formed, but which may be easily separated, by passing the liquor through blotting-paper. If the quantity of spirit employed be considerable, it may be drawn off by distillation in a glass retort: in the contrary case, the juice may be exposed for some time in a warm temperature, and the alkohol will readily evaporate, leaving a very clear acid of peculiar strength.

The citric acid affords an agreeable lemonade, by dissolving half a dram in two pints of water; adding a sufficient quantity of sugar, and bitter-sweet, which is prepared by rubbing the latter substance on fresh lemon-peels, till the essential oil be absorbed.  ACRE.—The English statute acre comprises 160 square poles, each of which contains $16 1⁄2$ feet. The same measure of land, in Scotland, is regulated by the Scotch ell, which is 372-10ths English inches: thus, 36 square ells make 1 fall; 40 falls, 1 rood; and 4 roods constitute an acre; so that the proportion of a Scotch to an English acre is nearly as that of 5 to 4.—The acre, employed in the Principality of Wales, is equivalent to 2 English ones; and the Irish acre is equal to 1 acre, 2 roods, and 19 perches 27-121 of English statute measurement.  AGRICULTURE.—Notwithstanding the fair prospects we have stated under, there are numerous obstacles that impede the progress of that inestimable art, in the British empire.—1. One of the most powerful impediments, is the general ignorance that still prevails among the managers of landed estates: this inconvenience, we are happy to observe, may gradually be removed, by establishments similar to