* ACID (MALIC.) The acid of apples; the same with that which is extracted from the fruit of the mountain ash. See ACID (SORBIC.*) * ACID (MARGARIC.) When we immerse soap made of pork-grease and potash, in a large quantity of water, one part is dissolved, while another part is precipitated, in the form of several brilliant pellets. These are separated, dried, washed in a large quantity of water, and then dried on a filter. They are now dissolved in boiling alcohol, sp. gr. 0.820, from which, as it cools, the pearly substance falls down pure. On acting on this with dilute muriatic acid, a substance of a peculiar kind, which M. Chevreul, the discoverer, calls margarine, or margaric acid, is separated. It must be well washed with water dissolved in boiling alcohol, from which it is recovered in the same crystalline pearly form, when the solution cools. Margaric acid is pearly white, and tasteless. Its smell is feeble, and a little similar to that of melted wax. Its specific gravity is inferior to water. It melts at 134o F. into a very limpid, colourless liquid, which crystallizes on cooling, into brilliant needles of the finest white. It is insoluble in water, but very soluble in alcohol, sp. gr. 0.800. Cold margaric acid has no action on the colour of litmus; but when heated so as to soften without melting, the blue was reddened. It combines with the salifiable bases, and forms neutral compounds. 100 parts of it unite to a quantity of base containing three parts of oxygen, supposing that 100 of potash contain 17 of oxygen. Two orders of margarates are formed, the margarates, and the supermargarates, the former being converted into the latter, by pouring a large quantity of water on them. Other fats besides that of the hog yield this substance. Acid. Base. Margarate of potash consists of 100 1777 100 8.88 100 12.72 100 28.93 100 20.23 100 11.06 Supermargarate Margarate of soda Barytes Strontites Lime tals disposed in stars, similar to the margaric acid of the hog. The margaric acids of man and the hog resemble each other; as do those of the ox and the sheep; and of the goose and the jaguar. The compounds with the bases, are real soaps. The solution of alcohol affords the transparent soap of this country. Annales de Chimie, several volumes.* * ACID (MECONIC). This acid is a constituent of opium. It was discovered by M. Sertuerner, who procured it in the following way: After precipitating the morphia, from a solution of opium, by ammonia, he added to the residual fluid a solution of the muriate of barytes. A precipitate is in this way formed, which is supposed to be a quadruple compound, of barytes, morphia, extract, and the meconic acid. The extract is removed by alcohol, and the barytes by sulphuric acid; when the meconic acid is left, merely in combination with a portion of the morphia; and from this it is purified by successive solutions and evaporations. The acid, when sublimed, forms long colourless needles; it has a strong affinity for the oxide of iron, so as to take it from the muriatic solution, and form with it a cherry-red precipitate It forms a crystallizable salt with lime, which is not decomposed by sulphuric acid; and what is curious, it seems to possess no particular power over the human body, when received into the stomach. The essential salt of opium, obtained in M. Derosne's original experiments, was probably the meconiate of morphia. Mr. Robiquet has made a useful modification of the process for extracting meconic acid. He treats the opium with magnesia, to separate the morphia, while meconiate of magnesia is also formed. The magnesia is removed by adding muriate of barytes, and the barytes is afterwards separated by dilute sulphuric acid. A larger proportion of meconic acid is thus obtained. Mr. Robiquet denies that meconic acid precipitates tes iron from the muriate; but, according to M. Vogel, its power of reddening dening sol solutions of iron is so great, as to render it a more delicate test of this metal, than even the prussiate of potash. To obtain pure meconic acid from the meconiate of barytes, M. Choulant triturated it in a mortar, with its own weight of glassy boracic acid. This mixture being put into a small glass flask, which was surrounded with sand in a sand pot, in the usual manner, and the red heat being gradually raised, the meconic acid sublimed, in the state of fine white scales or plates. It has a strong sour taste, which leaves behind it an impression of bitterness. It dissolves readily in water, alcohol, and ether. It reddens the greater number of vegeta As the potash and lime compounds give nearly the same acid ratio, we may take their mean of it, as the true prime = 2.8.* * ACID (MELASSIC). The acid present in melasses, which has been thought a peculiar acid by some, by others, the acetic.* ACID (MELLITIC). M. Klaproth discovered in the mellite, or honey-stone, what he conceives to be a peculiar acid of the vegetable kind, combined with alumina. This acid is easily obtained by reducing the stone to powder, and boiling it in about 70 times its weight of water; when the acid will dissolve, and may be separated from the alumina by filtration. By evaporating the solution, it may be obtained in the form of crystals. The following are its characters : It crystallizes in fine needles or globules by the union of these, or small prisms. Its taste is at first a sweetish sour, which leaves a bitterness behind. On a plate of hot metal it is readily decomposed, and dissipated in copious gray fumes, which affect not the smell; leaving behind a small quantity of ashes, that do not change either red or blue tincture of litmus. Neutralized by potash it crystallizes in groups of long prisms: by soda, in cubes, or triangular lamina, sometimes in groups, sometimes single; and by ammonia, in beautiful prisms with six planes, which soon lose their transparency, and acquire a silvery white hue. If the mellitic acid be dissolved in lime-water, and a solution of calcined strontian or barytes be dropped into it, a white precipitate is thrown down, which is redissolved on adding muriatic acid. With a solution of acetate of barytes, it produces likewise a white precipitate, which nitric acid redissolves. With solution of muriate of barytes, it produces no precipitate, or even cloud; but after standing some time, fine transparent needly crystals are deposited. The mellitic acid produces no change in a solution of nitrate of silver. From a solution of nitrate of mercury, either hot or cold, it throws down a copious white precipitate, which an addition of nitric acid immediately redissolves. With nitrate of iron it gives an abundant precipitate of a dun yellow colour, which may be redissolved by muri muriatic acid. With a solution of acetate of lead, it produces an abundant precipitate, immediately redissolved on adding nitric acid. With acetate of copper, it produces a grayish-green precipitate; but it does not affect a solution of muriate of copper. Lime-water precipitated by it, is immediately redissolved on adding nitric acid. M. Klaproth was never able to convert this acid into the oxalic by means of nitric acid, which only changed its brownish colour to a pale yellow. * The mellite, or native mellate of alumina, consists, according to Klaproth, of 46 acid + 16 alumina + 38 water = 100; from which, calling the prime of alumina 3.2, that of mellitic acid appears to be 9.2.* * ACID (MENISPERMIC). The seeds of menispermum cocculus being macerated for 24 hours in 5 times their weight of water, first cold, and then boiling hot, yield an infusion, from which solution of subacetate of lead throws down a menispermate of lead. This is to be washed and drained, diffused through water, and decomposed by a current of sulphuretted hydrogen gas. The liquid thus freed from lead, is to be deprived of sulphuretted hydrogen by heat, and then forms solution of minispermic acid. By repeated evaporations and solutions in alcohol, it loses its bitter taste, and becomes a purer acid. It occasions no precipitate with lime-water; with nitrate of barytes it yields a gray precipitate; with nitrate of silver, a deep yellow; and with sulphate of magnesia, a copious precipitate.* * ACID (MOLYBDIC). The native sulphu. ret of molybdenum being roasted for some time, and dissolved in water of ammonia, when nitric acid is added to this solution, the molybdic acid precipitates in fine white scales, which become yellow, on melting and subliming them. It changes the vegetable blues to red, but less readily and powerfully than the following acid. M. Bucholz found that 100 parts of the sulphuret gave 90 parts of molybdic acid. In other experiments in which he oxidized molybdenum, he found that 100 of the metal combined with from 49 to 50 of oxygen. Berzelius, after some vain attempts to analyze the molybdates of lead and barytes, found that the only method of obtaining an exact result was to form a molybdate of lead. He dissolved 10 parts of neutral nitrate of lead in water, and poured an excess of solution of crystallized molybdate of ammonia into the liquid. The molybdate of lead, washed, dried and heated to redness, weighed 11.068. No traces of lead were found in the liquid by sulphate of ammonia; hence these 11.068 of lead, evince 67.3 per cent of oxide of read. This salt then is composed of Molybdic acid 39.194 Oxide of lead 60.806 100.000 9.0 14.0 And from Bucholz we infer, that this prime equivalent 9, consists of 3 of oxy gen + 6 metal; while molybdous acid will be 2 oxygen + 6 metal = 8.0. Molybdic acid has a specific gravity of 3.460. In an open vessel it sublimes into brilliant yellow scales; 960 parts of boiling water dissolve one of it, affording a pale yellow solution, which reddens litmus, but has no taste. Sulphur, charcoal, and several metals decompose the molybdic acid. Molybdate of potash is a colourless salt. Molybdic acid gives, with nitrate of lead, a white precipitate, soluble in nitric acid; with the nitrates of mercury and silver, a white flaky precipitate; with nitrate of copper, a greenish precipitate; with solutions of the neutral sulphate of zinc, muriate of bismuth, muriate of antimony, nitrate of nickel, muriates of gold and platinum, it produces white precipitates. When melted with borax, it yields a bluish colour; and paper dipped in its solution becomes, in the sun, of a beautiful blue.* The neutral alkaline molybdates preci pitate all metallic solutions. Gold, muriate of mercury, zinc, and manganese, are precipitated in the form of a white powder; iron and tin, from their solutions in muriatic acid, of a brown colour; cobalt, of a rose colour; copper, blue; and the solutions of alum and quicklime, white. If a dilute solution of recent muriate of tin be precipitated by a dilute solution of molybdate of potash, a beautiful blue powder is obtained. The concentrated sulphuric acid dissolves a considerable quantity of the molybdic acid, the solution becoming of a fine blue colour as it cools, at the same time that it thickens; the colour disappears again on the application of heat, but returns again by cooling. A strong heat expels the sulphuric acid. The nitric acid has no effect on it; but the muriatic dissolves it in considerable quantity, and leaves a dark blue residuum when distilled. With a strong heat it expels a portion of sulphuric acid from sulphate of potash. It also disengages the acid from nitre and common salt by distillation. It has some action upon the filings of the me tals in the moist way. The molybdic acid has not yet been employed in the arts. * ACID (MOLYBDOUS). The deutoxide of molybdenum is of a blue colour, and possesses acid properties. Triturate 2 parts of molybdic acid, with 1 part of the metal, along with a little hot water, in a porcelain mortar, till the mixture assumes a blue colour. Digest in 10 parts of boiling water, filter, and evaporate the liquid in a heat of 120°. The blue oxide separates. It reddens vegetable blues, and forms salts with the bases. Air or water, when left for some time to act on molybdenum, convert it into this acid. It consists of about 100 metal to 34 oxygen,* ACID (MOROXYLIC). In the botanic garden at Palermo, Mr. Thompson found an uncommon saline substance on the trunk of a white mulberry tree. It appeared as a coating on the surface of the bark in little granulous drops of a yellowish and blackish brown colour, and had likewise penetrated its substance. M. Klaproth, who analyzed it, found that its taste was somewhat like that of succinic acid; on burning coals it swelled up a little, emitted a pungent vapour scarcely visible to the eye, and left a slight earthy residuum. Six hundred grains of the bark loaded with it were lixiviated with water, and afforded 320 grains of a light salt, resembling in colour a light wood, and composed of short needles united in radii. It was not deliquescent; and though the crystals did not form till the solution was greatly condensed by evaporation, it is not very soluble, since 1000 parts of water dissolve but 35 with heat, and 15 cold. This salt was found to be a compound of lime and a peculiar vegetable acid, with some extractive matter. To obtain the acid separate, M. Klaproth decomposed the calcareous salt by acetate of lead, and separated the lead by sulphuric acid. He likewise decomposed it directly by sulphuric acid. The product was still more like succinic acid in taste; was not deliquescent; easily dissolved both in water and alcohol; and did not precipitate the metallic solutions, as it did in combination with lime. Twenty grains being slightly heated in a small glass retort, a number of drops of an acid liquor first came over; next a concrete salt arose, that adhered flat against the top and part of the neck of the retort in the form of prismatic crystals, colourless and transparent; and a coaly residuum remained. The acid was then washed out, and crystallized by spontaneous evaporation. Thus sublimation appears to be the best mode of purifying the salt, but it adhered too strongly to the lime to be separated from it directly by heat without being decomposed. Not having a sufficient quantity to determine its specific characters, though he conceives it to be a peculiar acid, coming nearest to the succinic both in taste and other qualities, ties, Mr. Klaproth has provisionally given it the name of moroxylic, and the calcareous salt containing it that of moroxylate of lime. ACID (MUCIC). This acid has been generally known by the name of saccholactic, because it was first obtained from sugar of milk; but as all the gums appear to afford it, and the principal acid in sugar of milk is the oxalic, chemists in general now distinguish it by the name of mucic acid. It was discovered by Scheele. Having poured twelve ounces of diluted nitric acid on four ounces of powdered sugar of milk in a glass retort on a sand bath, the mixture became gradually hot, and at length effervesced violently, and continued to do so for a considerable time after the retort was taken from the fire. It is necessary therefore to use a large retort, and not to lute the receiver too tight. The effervescence having nearly subsided, the retort was again placed on the sand heat, and the nitric acid distilled off, till the mass had acquired a yellowish colour. This exhibiting no crystals, eight ounces more of the same acid were added, and the distillation repeated, till the yellow colour of the fluid disappeared. As the fluid was inspissated by cooling, it was redissolved in eight ounces of water, and filtered. The filtered liquor held oxalic acid in solution, and seven drams and a [8] VOL. I half of a white powder remained on the filter. This powder was the acid under consideration. If one part of gum be heated gently with two of nitric acid, till a small quantity of nitrous gas and of carbonic acid is disengaged, the dissolved mass will deposite on cooling the mucic acid. According to Fourcroy and Vauquelin, different gums yield from 14 to 26 hundredths of this acid. This pulverulent acid is soluble in about 60 parts of hot water, and by cooling, a fourth part separates in small shining scales, that grow white in the air. It decomposes the muriate of barytes, and both the nitrate and muriate of lime. It acts very little on the metals, but forms with their oxides salts scarcely soluble. It precipitates the nitrates of silver, lead, and mercury. With potash it forms a salt soluble in eight parts of boiling water, and crystallizable by cooling. That of soda requires but five parts of water, and is equally crystallizable. Both these salts are still more soluble when the acid is in excess. That of ammonia is deprived of its base by heat. The salts of barytes, lime, and magnesia, are nearly insoluble. * Mucic or saccholactic acid has been analyzed recently with much care; Hydrogen. Carbon. Oxygen. Gay-Lussac, 3.62+33.69 + 62.69 =100 Berzelius, 5.105 +33.430+61.465=100 From saclactate of lead, Berzelius has inferred the prime equivalent of the acid to be 13.1.* * ACID (MURIATIC). Let 6 parts of pure and well dried sea salt be put into a glass retort, to the beak of which is luted, in a horizontal direction, a long glass tube artificially refrigerated, and containing a quantity of ignited muriate of lime. Upon the salt pour at intervals 5 parts of concentrated oil of vitriol, through a syphon funnel, fixed, air-tight, in the tubulure of the retort. The free end of the long tube being recurved, so as to dip into the mercury of a pneumatic trough, a gas will issue, which on coming in contact with the air, will form a visible cloud, or haze, presenting, when viewed in a vivid light, prismatic colours. This gas is muriatic acid. When received in glass jars over dry mercury, it is invisible, and possesses all the mechanical properties of air. Its odour is pungent and peculiar. Its taste acid and corrosive. Its specific gravity, according to Sir H. Davy, is such, that 100 cubic inches weigh 39 grains, while by estimation, he says, they ought to be 38.4 gr. By the latter number the specific gravity, compared to air, becomes 1.2590. By the former number the density comes out 1.2800. M. GayLussac states the sp. gr. at 1.2780. Sir H.'s second number makes the prime equiva lent of chlorine 4.43, which comes near to Berzelius's latest result; while his first number makes it 4.48, (See CHLORINE). As the attraction of muriatic acid gas for hygrometric water is very strong, it is very probable that 38.4 grs. may be the more exact weight of 100 cubic inches, regarding the same bulk of air as = 30.5. If an inflamed taper be immersed in it, it is instantly extinguished. It is destructive of animal life; but the irritation produced by it on the epiglottis scarcely permits its descent into the lungs. It is merely changed in bulk by alterations of temperature; it experiences no change of state. When potassium, tin, or zinc, is heated in contact with this gas over mercury, one-half of the volume disappears, and the remainder is pure hydrogen. On examining the solid residue, it is found to be a metallic chloride. Hence muriatic acid gas consists of chlorine and hydrogen, united in equal volumes. This view of its nature was originally given by Scheele, though obscured by terms derived from the vague and visionary hypothesis of phlogiston. The French school afterwards introduced the belief that muriatic acid gas was a compound of an unknown radical and water; and that chlorine consisted of this radical and oxygen. Sir H. Davy has the distinguished glory of refuting the French hypothesis, sis, and of proving by decisive experiments, that in the present state of our knowledge, chlorine must be regarded a simple substance; and muriatic acid gas as a compound of it with hydrogen. as This gaseous acid unites rapidly, and in large quantity, with water. The following table of its aqueous combinations, was constructed after experiments made by Mr. E. Davy, in the laboratory of the Royal Institution, under the inspection of Sir H. Davy. At temperature 45°, barometer 30. 100 parts of solution of muriatic gas, in water, of sp. gravity contain At the temperature of 40° Fahrenheit, water absorbs about 480 times its bulk of gas, and forms solution of muriatic acid gas in water, the specific gravity of which is 1.2109.-Sir H. Davy's Elements. In In the Annals of Philosophy for October and November 1817, there are two papers on the constitution of liquid muriatic acid with tables, by Dr. Ure, which coincide nearly with the preceding results. They were founded on a great number of experiments carefully performed, which are detailed in the October number. mixing strong liquid acid with water, he found that some heat is evolved, and a small condensation of volume is experienced, contrary to the observation of Mr. Kirwan. Hence this acid forms no longer an exception, as that eminent chemist taught, to the general law of condensation of volume, which liquid acids obey in their progressive dilutions. Hitherto indeed many chemists have, without due consideration, assumed the half-sum or arithmetical mean of two specific gravities, to be the truly computed mean; and on comparing the number thus obtained with that derived from experiment, they have inferred the change of of volume, volume, occasioned by chemical combination. The errors into which this false mode of computation leads are excessively great, when the two bodies differ considerably in their specific gravities. A view of these erroneous results was given in Dr. Ure's third table of sulphuric acid, published in the 7th number of the Journal of Sciences and the Arts, and reprinted in this Dictionary, article SPECIFIC GRAVITY. When, however, the two specific gravities do not differ much, the errors become less remarkable. Of muriatic acid It is a singular fact, that the arithmetical 1.21 42.43 1.20 40.80 1.19 38.38 1.17 34.34 1.16 32.32 1.15 30.30 1.14 28.28 10.10 1.04 8.08 1.03 6.06 |