Citric acid

“ Action of Citric Acid on Minerals.—Professor H. C. Bolton read a third paper at the recent meeting of the American Association on the decomposition of minerals by citric acid, detailing the results of his later researches on the subject. ”

“ The acid is thus obtained in colourless rhombic prisms of the composition C6H8O7 + H2O. Crystals of a different form are deposited from a strong boiling solution of the acid. About 20 gallons of lemon juice should yield about 10 lb of crystallized citric acid. The acid may also be prepared from the juice of unripe gooseberries. Calcium citrate must be manufactured with care to avoid an excess of chalk or lime, which would precipitate constituents of the juice that cause the fermentation of the citrate and the production of calcium acetate and butyrate. ”

“ In the third series of experiments Professor Bolton found that many species which resist the brief action of a boiling concentrated solution of citric acid are more or less completely decomposed by prolonged contact with the same solution at the ordinary temperature of the work-room. He has drawn up a table, in accordance with the last series of tests, of thirty-two minerals or classes of minerals which are classified as those that are quickly, slowly, very slowly, or not, decomposed by citric acid. ”

“ When the aqueous solution of citric acid obtained, as already described, is concentrated by boiling in an open evaporating pan, the acid is not only liable to suffer partial decomposition by its long exposure to the air, but it not unfrequently acquires a brown colour from the carbonisation those portions of the liquid undergo which are in contact with the bottom of the pan, which being heated by high-pressure steam frequently reaches a temperature exceeding 200° F. This latter result is brought about in consequence of the slight movement in the dense acid liquor in the pan. ”

“ A mixture of iron filings and citric acid, in powder, with barely sufficient water to cover it, is kept in a warm situation for some days, occasionally stirring the mass, and replacing the water as it evaporates. A saturated solution is next made in distilled water, there being previously added more citric acid (about half the weight of the acid first used) , as required; it is then neutralised with liquor of ammonia (about 11⁄4 oz. of liquor of ammonia, sp. gr. ·882, to every gallon of the solution of sp. gr. 1·025) , and the solution is concentrated by evaporation ”

“ Sometimes a little nitric acid is added to the solution of the coloured crystals, for the purpose of bleaching them, but in this way a minute quantity of oxalic acid is formed. A more general plan is to bleach the citrate of lime by covering it with a weak solution of chloride of lime, exposing it in shallow vessels to the sun’s rays, and rewashing it before decomposing it with sulphuric acid. A safer plan is to dissolve the crude citric acid, digest with animal charcoal, and again concentrate the solution to the crystallising point. ”

“ If tartaric acid be present, a white, crystalline precipitate of cream of tartar will be produced on agitation. When pure it is devoid of colour, is entirely, or almost entirely, decomposed by heat. It is soluble in water and in spirit, and what is thrown down from its watery solution by acetate of lead is dissolved by nitric acid. No salt of potassium precipitates anything with citric acid except the tartrate. When a few drops of a solution of citric acid are added to lime water, a clear liquid results, which, when heated, deposits a white powder, soluble in acids without effervescence. ”

“ Protocitrate of iron, Citrate of protoxide of iron. This salt is easily formed by digesting iron filings or wire with citric acid, and evaporating the solution as quickly as possible out of contact with the air. It presents the appearance of a white powder, nearly insoluble in water, and rapidly passing to a higher state of oxidation by exposure to the air. Its taste is very metallic. It is exhibited under the form of pills, mixed with gum or syrup, to prevent it from being prematurely decomposed. ”

“ To prevent the accession of rancidity, a little benzoic acid, gum benzoin, or nitric ether may be added to the fat, whilst in the liquid state, as noticed under Fat and Ointment. Sometimes a small portion of white wax or beeswax (according to the intended colour of the product) is melted with the fat to increase its solidity. Some parties employ a few grains of powdered citric acid per ounce, in a like manner, with the intention of increasing the whiteness of the compound; but the practice is not to be commended, as pommades so prepared prove injurious to the hair. ”

“ Citric acid is a commodity always, everywhere, and increasingly in demand. The lime belt is narrow and limited. Ours is the most productive in the world. The limes are larger than those of any other country and the percentage of acid is perceptibly greater. Fortunes await in this department of industry alone, and the outlay of money to get a start is insignificant compared to the planting of an orange grove. ”

“ The accomplishment of such an effect is in many instances the sole object of a pharmaceutical process. It is thus that we obtain pure Citric acid from the juice of the Lemon; Tartaric acid, from Cream of Tartar; Benzoic acid, from the resinous substance known by the name of Gum Benzoin; upon the same principle, the Muriatic and Nitric acids are elicited from the saline compounds in which they exist. Ammonia, in its pungent form, is developed from its inodorous Muriate ”

“ But, although that is not absolutely necessary, we would advise one working this, or similar processes in which a silver salt is employed for developing, to fix the image, after treatment with citric acid to clear the proofs from iron salts, in a solution of ammonium sulphocyanate—which has not the injurious effect of sodium thiosulphate (hyposulphite) —in order to prevent the paper to be tinged by the reduction of the silver nitrate which is mechanically retained in its fiber. ”

“ Sicilian juice in November yields about 9 oz. of crude citric acid per gallon, but only 6 oz. if the fruit is collected in April. The crude juice was formerly exported to England, and was often adulterated with sea-water, but is now almost entirely replaced by lime juice. A concentrated lemon juice for the manufacture of citric acid is prepared in considerable quantities, chiefly at Messina and Palermo, by boiling down the crude juice in copper vessels over an open fire until its specific gravity is about 1.239, seven to ten pipes of raw making only one of concentrated lemon juice. ”

“ This explanation seemed logical in view of the marked potency of the citrous fruits, and particularly when it was shown that human milk contains a greater percentage of the salts of citric acid than cow’s milk, and that some of these salts are lost in the course of heating. This hypothesis withstood neither the practical test nor chemical investigation. It was found that the various salts of citric acid, either singly or in combination, are unable to cure scurvy. This treatment has been employed repeatedly on man and on animals with little or no success ”

“ Solution of the Reverted Phosphates by Ammonium Citrate.—The filter from the above process is detached from the funnel and is introduced into a flask marked at 150 cubic centimeters together with sixty cubic centimeters of alkaline ammonium citrate prepared in the following manner:
Pure citric acid, 400 grams. Ammonia of 22°, 500 cubic centimeters.
The ammonia is poured upon the citric acid in the form of crystals in a large dish. The mass becomes heated, and the solution takes place rapidly. ”

“ The ammonium carbonate should be almost transparent and free from white powder, and should be dissolved in cold [Pg 21] water, while the ammonium citrate employed should be neutral. Most samples contain acid, which acid would neutralize the ammonium carbonate and affect the resulting tone. The free acid is usually citric acid, and should be neutralized with a solution of ammonia using litmus as indicator.
Temperature of Toning—To obtain the best results the temperature of the bath should be from 65 degrees to 70 degrees F.
Time of Toning—Five to ten minutes. ”

“ Remedies which are apparently opposed in nature have proved useful in these complaints. On the Restorative plan, alkalies are the remedies required; for they neutralize the acid. But in spite of this excess of acid, some of the free vegetable acids have been used with advantage, particularly in rheumatic cases. We shall have hereafter to consider how far this operation resembles the common refrigerant action of these remedies just now considered. (Vide Antiarthritics.) Some obscurity rests upon the subject of the use of Citric acid in scurvy ”

“ The precipitate is collected and washed with 30 of water. Citric acid 3 is dissolved in 8 of water by the aid of a water bath, and the ferric hydrate, well drained, added; stir together until dissolved, and add the quinine, stirring well until all is dissolved, and allow to cool; add 11⁄2 of solution of ammonia diluted with 2 of water, stirring the solution briskly until the quinine at first thrown down by the ammonia is redissolved; filter and evaporate to a syrup, drying in thin layers on flat porcelain or glass plates at a temperature of 100°. ”

“ 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. ”

“ In most cases a simple ignition is sufficient, while, if the phosphorus be found in certain organic products, the oxidation must be accomplished by one of the methods described in the processes adopted by the official chemists, or by the means described in volume first, paragraph 378 or 382. In all cases of acid phosphates and superphosphates, the water and ammonium citrate soluble phosphoric acid is to be determined as well as the total. In basic slags the amount soluble in ammonium citrate or dilute citric acid is also to be ascertained. ”

“ It was when he quaffed the new and stronger draught that Jon knew that his hope that it was citric acid was squelched.
The acid taste was weaker which meant that the citric acid was the diluting liquid. It was the liquid he couldn't taste beneath the tang of the citric acid that was the corrosive acid.
On the fourteenth day, Jon was so weak he didn't feel much like moving around. He let the cylinder feed him the hemlock.
No. 1 came again to see him, and went away chuckling, "Decrease the dilution. This Earthman at last is beginning to suffer." ”

“ I have found, for instance, that the more complex citric acid molecule offers a more favorable source of energy to a denitrifying organism that I have isolated than do either succinic, tartaric or lactic acid. And the laboratory work clearly indicates that the amount of organic substance in the soil, as well as its nature, determines the course of development, and the prevalence of the one or the other of the soil organisms. Certain it is that where the fixation of nitrogen takes place in the soil, it occurs only when its store of nitrogen is very meager. ”

“ A high temperature must be avoided.
2. (Robiquet.) Citric acid, 351⁄4 parts, is powdered and dissolved in boiling water, 105⁄8 parts; when the solution is cold, and before it crystallises, it is poured in a wide earthen vessel, kept cold by surrounding it with water; then, by means of a sieve, carbonate of magnesium, 211⁄6 parts, is distributed evenly and rapidly over the surface without stirring; when the reaction ceases the mixture is beaten rapidly as long as it retains its pasty consistence. The salt should be dried at a temperature not exceeding 70° Fahr. ”

“ It abounds in a pale yellow acid juice having a pleasant sour taste and a slight peculiar odour quite distinct from that of the peel. When removed from the pulp by pressure, the juice appears as a rather turbid yellowish fluid having a sp. gr. which varies from 1·040 to 1·045, and containing in each fluid ounce from 40 to 46 grains of citric acid, or about 91⁄2 per cent. [463] In Italy all the fine and perfect fruit is exported; the windfalls and the damaged fruit are used for the production of the essential oil and the juice. ”

“ Water-Soluble Phosphoric Acid.—Add twenty cubic centimeters of citric acid solution to fifty cubic centimeters of the water-soluble solution obtained according to the Swedish molybdenum method, and then add thirty-three cubic centimeters of ammonia. When the mixture has cooled, add slowly twenty-five cubic centimeters of the magnesia mixture, and then forty-two cubic centimeters of the ammonia. Keep the solution stirred by means of a closely clipped feather which is pressed tightly against the sides of the beaker ”

“ The later colouration reminds one of that assumed by starch granules under similar circumstances; yet on addition of a very dilute solution of iodine, the granules always exhibit a blackish, not a blue tint, so that they are not to be considered as starch granules. The hairs of the pulp are formed of a single, thick-walled cell, straight or sometimes a little crooked. [Pg 269]
Chemical Composition—The pulp examined by Biltz (1824) was found to afford nearly 3 per cent. of citric acid, 7·7 of malic acid, besides citrates, malates and mineral salts, 25 per cent. ”