MALIC acid, in chemistry, was disco vered by Scheele about the year 1785. It is found in the juices of a great many fruits, and it derives its name from the circumstance of its being obtained in great abundance from the juice of apples, in which it exists ready formed. It is thus obtained : saturate the juice of apples with potash, and add to the solution ace tate of lead till no more precipitation en sues. Wash the precipitate carefully with a sufficient quantity of water; then pour upon it diluted sulphuric acid till the mixture has a perfectly acid taste, without any of that sweetness which is perceptible as long as any lead remains dissolved in it ; then separate the sulphate of lead, which has precipitated, by filtra tion, and there remains behind pure malic acid. The French chemists have ascer tained that it may be obtained in the largest quantities from the juice of the sempervivum tectorum, where it exists abundantly combined with lime. Malic
acid is very soluble in water, and decom poses spontaneously, by undergoing a kind of fermentation. It is composed of oxygen, hydrogen, and carbon. It com bines with alkalies, earths, and metallic oxides, and forms MALATES, which see above.
Dr. Thomson has shewn in what the citric and malic acids agree, and in what they differ. The citric acid shoots into crystals; but the malic will not crystal lize. The citrate of lime is almost inso luble in boiling water, but the malate of lime is easily soluble in that liquid. Malic acid precipitates mercury, lead, and sil ver, from the nitrous acid, and likewise the solution of gold when diluted with water ; whereas the citric acid does not alter any of these solutions.