Chemistry : general, medical, and pharmaceutical including the chemistry of the British Pharmacopœia a manual on the general principles of the science, and their applications in medicine and pharmacy / by John Attfield.

  • Attfield, John, 1835-1911.
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry : general, medical, and pharmaceutical including the chemistry of the British Pharmacopœia a manual on the general principles of the science, and their applications in medicine and pharmacy / by John Attfield. Source: Wellcome Collection.

    681/850 (page 647)
    This will be dae in fclie fii-sfc place to carbonic acid liberated and retnaining dissolved in the solution. The contents of the flask are therefore boiled for several minutes, when the blue colour will have returned. More acid is then ran in until the mix- ture, after boiling, remains of a neutral colour, indicating that just enough acid has been added to complete the reaction ex- pressed in the foregoing equation. Let it be supposed that 6 grammes of carbonate of sodium were taken, and that this required 11 c. c. of oxalic acid solu- tion, how many c. c. of this solution would contain 63 grammes of oxalic acid crystals ; or, what is equivalent in the reac- tion, how many c. c. would be required to neutralize 53 grammes of carbonate of sodium ? As 6 grammes Na2C03 are to 11 c. c. sol., so are 53 grammes Na^COg to x c. c. sol. a; = 972 c. c. 972 c. c. (neai'ly) are equivalent to 53 grammes of cai'bonate of sodium, and contain 63 gi-ammes of oxalic acid. This solution may either be used as it is or may be diluted with water, every 972 c. c. to be diluted to 1000 c. c, so that 1000 c. c. shall contain 63 grammes of oxalic acid. The following official substances are tested by this solution according to the British and United States Pharmacopoeias :— Solutions of Ammonia.—Two or 3 grammes of dilute, or about 1 gramme of strong solution of ammonia, is a convenient quantity to operate upon. The weighing is most conveniently accomplished by taking a small stoppered bottle containing half an ounce or so of the substance, and having ascertained its total weight, transfer about the quantity desired to the flask in which the estimation is to be conducted, and again weigh the bottle with what remains in it. The diSerence is the exact quantity taken. The weighing of the ammonia solution having been accomplished, water is added, to about one-third the capacity of the flask (or, better, the ammonia is added to water already in the flask), and a few drops of tincture of litmus introduced. The titration is then con. ducted as described before, except that no heat is employed. 2NH^H0 + H2C.Q,2H3Q = (NHJ^CgO^ + 4H2O 2)70 2)126 35 63 = grammes in 1000 c. o. of standard solution. 2NH3 H.O -t- HjCASH^ = (NHJaCgO.i -t- 4H2O 2^34^ 2)126