The pharmacopoeia of the United States of America, 1850.

  • General Medical Convention.
Date:
1851
Catalogue details

Licence: Public Domain Mark

Credit: The pharmacopoeia of the United States of America, 1850. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    64/1902
    Chalk by degrees till there is no more effervescence. Collect the deposit on a calico filter, and wash it with hot water till the filtered liquor passes from it colourless. Mix the deposit with a pint [Imp. meas.] of Distilled Water, and gradually add the Sulphuric Acid previously diluted with a pint and a half [Imp. meas.] of Distilled Water. Boil gently for half an hour, keeping the mixture constantly stirred. Sepa- rate the acid solution by filtration, wash the insoluble matter with a little Distilled Water, and add the washings to the solution. Concentrate the solution to the den- sity of 1*21, then allow it to cool, and after twenty-four hours decant the liquor from the crystals of sulphate of lime which have formed; further concentrate the liquor until a film forms on its surface, an^set it aside to cool and crystallize. Purify the crystals if necessary by a recrystallization.” Br. A preliminary fermentation, which was directed in the former British Pharmaco- poeia, has been abandoned in the present; and properly, as the viscidity which it was intended to remove, is sufficiently got rid of by heating the juice to the boiling point. The Br. Pharmacopoeia states, as an evidence of the purity of the crystals, that “70 grains dissolved in distilled water are neutralized by 1000 grain-measures of the volu- metric solution of soda.” Preparation on the Large Scale. The juice is placed in a large vat, closed at top, and is saturated with whiting (carbonate of calcium). Carbonic acid gas is evolved, which passes out by an exit-pipe, and may be used in the manufacture of bicarbonate of sodium; and citrate of calcium precipitates. The supernatant liquor, containing much extractive matter, is drawn off; and the citrate of calcium is decomposed by dilute sulphuric acid, liberating the citric acid, and precipitating the lime as a sulphate. The mixture of citric acid and sulphate of calcium is run off into a wooden filter back, lined with lead, furnished with a perforated false bottom, and lined throughout with stout twilled flannel. The solution of citric acid passes off through a pipe, leading from the bottom of the back to suitable reservoirs. The sulphate is washed until it becomes tasteless, and the washings are run off into the same reservoirs. The filtered acid solution is then concentrated by evaporation in wooden vessels lined with lead, through which steam is made to pass by means of coiled lead pipes. As citric acid is liable to decomposition, if subjected to too high a temperature, the use of the vacuum pan is highly advantageous in concentrating the solution. When the liquor is sufficiently concentrated, it is transferred to cylindrical sheet-lead vessels, placed in a warm situation, to crystallize. The crystals, at first obtained, are coloured. In order to purify them, they are redissolved in a small quantity of water, with the assistance of heat, and the solution is digested with purified animal charcoal, filtered, and recrystallized. The crystals, after having been washed and drained, are dried on wooden trays lined with sheet-lead, in a room heated by steam. More recently, Dr. Price and Mr. Pontifex, both of England, have made improvements in the manufacture of citric acid, for the details of which the reader is referred to the Pharmaceutical Journal and Transactions (xiii. 313, and xvi. 430).* * Some suggestions have recently appeared in the journals, in relation to the preparation of citric acid on the large scale, which may he of use to the manufacturer. In the Chemical A7eics (Jan. 20, 1866, p. 40) is a short paper by Mr. Frederick Row, in which it is stated that the lemon or lime juice imported, from which most of the acid is prepared, contains so much colouring matter, muci- lage, and other impurities, as very much to impede the process, and to make repeated crystallization and saturation necessary, to render the crystals fit for the market. It seems that the acid imported has undergone concentration, for the obvious purposes of enabling it to keep better, and to lessen the cost of carriage. Mr. Row states that he has found that much of the difficulty may he obviated by diluting the concentrated liquor, so that it shall have the strength of the fresh juice, by which operation much of the mucilage and other impurities will be made to separate in a flocculent form, and the citrate of calcium, and consequently the citric acid, will be obtained in a state of compara- tive purity. Another important point is that the sulphuric acid, in slight excess at first, accumulates largely in proportion with the repeated evaporation and crystallization of the citric acid out of the solu- tions, and thus exercises a most destructive action on that remaining in the mother-liquors. The most effectual way of removing this difficulty is to pass the mother-liquors, as soon as the sulphuric acid becomes in injurious excess, through a fresh portion of citrate of calcium, which not only re- moves the sulphuric acid, but causes also at the same time the deposition of flocculent matters before held in solution by means of the acid, consisting mainly of sulphate of calcium. Preparation of citric acid loith the aid of magnesia. M. Perret proposes to manufacture citric acid by preparing from the juice, in the situations where lemons and limes are produced, first an insolu- ble tribasic citrate of magnesium, and then from this a soluble bibasic citrate of magnesium, which