Chemistry : general, medical, and pharmaceutical including the chemistry of the British pharmacopoeia a manual on the science of chemistry, and its applications in medicine and pharmacy / by John Attfield ; edited by Leonard Dobbin.

  • Dobbin Leonard.
Date:
1903
Catalogue details

Licence: In copyright

Credit: Chemistry : general, medical, and pharmaceutical including the chemistry of the British pharmacopoeia a manual on the science of chemistry, and its applications in medicine and pharmacy / by John Attfield ; edited by Leonard Dobbin. Source: Wellcome Collection.

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

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    Ammonium Oxalate Experiment 6.—To a nearly boiling solution of 1 part of oxalic acid in about 8 of water add ammonium carbonate until the liquid is neutral to test-paper (see following para- graphs), filter while hot, and set aside to crystallize. The product is Ammonium Oxalate, B.P., (NHJ.OOj, IT,0, or (COONH4).„ H .O. A solution of it is used as a reagent in analysis; 1 part of the pure salt in 40 of water forms “Solution of Ammonium Oxalate,” B.P. 3H,C,0, + 2N3HnC,05 = 3(NH4)2C,04 + 4CO, + 2HL,0 Oxalic “Ammonium Ammonium Carbonic Water acid carbonate ” oxalate anhydride Neutralization.—Thus far the methods by which the student has avoided excess of either acid matter on the one hand, or alkaline on the other, have been the rough aid of taste, cessation of effervescence, presence or absence of odour, etc. M ore delicate aid is afforded by test-papers. Test-papers.—Litmus (B.P.) is a blue vegetable pigment, prepared from various species of Roccella lichen, exceedingly sensitive to the action of acids, which turn it red. When thus reddened, alkalies (caustic potash or soda, and ammonia) and other soluble hydroxides, also alkali-metal carbonates, etc., readily turn it blue. The student should here test for him- self the delicacy of this action by experiments with paper soaked in solution of litmus and dipped into very dilute solutions of acids, acid salts (e.g. KHC4H4O0), alkalies, and such neutral salts as potassium nitrate, sodium sulphate, or ammonium chloride. Solution of Litmus (B.P.).—This is prepared from purified litmus. Gently boil litmus with four times its bulk of alcohol (90 per cent.) for an hour. Pour away the fluid and repeat the operation twice. Digest the residual litmus in distilled water and filter. Blue litmus-paper (B.P.) is “made by impregnating un- glazed white paper with a solution of litmus.” Red litmus- paper (B.P.) is “made by impregnating unglazed white paper with solution of litmus reddened by the previous addition of a very minute quantity of sulphuric acid.” Turmeric paper (B.P.) similarly prepared from Tincture of I urmeric (B.P.) (1 of turmeric root or rhizome to fi> of