Companion to the latest edition of the British pharmacopoeia : comparing the strength of its various preparations with those of the United States and other foreign pharmacopoeias to which are added non-official preparations and practical hints on prescribing / by Peter Squire.

  • Squire, Peter Wyatt, Sir, 1847-1919.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Companion to the latest edition of the British pharmacopoeia : comparing the strength of its various preparations with those of the United States and other foreign pharmacopoeias to which are added non-official preparations and practical hints on prescribing / by Peter Squire. Source: Wellcome Collection.

    347/480 (page 311)
    employed in testing are expressed in cubic centimetres,—the cubic centimetre being the volume of a gramme of Distilled Water. As the cubic centimetre bears the same relation to the gramme that the grain- measure bears to the grain, the one system may be substituted for the other with no diiference in the results, excepting that, by the metrical system, all the quan- tities will be expressed in relation to a weight (the gramme) which is fifteen times greater than the British grain. In practice it will be found convenient in substituting metrical for British weights and measures, to reduce the values of all the numbers to one-tenth, by moving the decimal points, and this has been done in the tables appended to the descriptions of the volumetric solutions. The quantities indicated in the Pharma- copoeia, which in grains and grain-measures can be conveniently used, would be found inconveniently large if the same numbers of grammes and cubic centimetres were employed. The following apparatus is required in the preparation and use of these solutions. For British weights and measures :— 1. A flask, which when filled to a mark on the neck, contains exactly 10,000 grains of Distilled Water at 60°. The capacity of the flask is therefore 10,000 g^ain-measures. 2. A graduated cylindrical jar, which, when filled to 0, holds 10,000 grains of DistilledWater, and is divided into 100 equal parts. 3. A burette. A graduated glass tube which, when filled to 0, holds 1000 grains of Distilled V/ater, and is divided into 100 equal parts. Each part there- fore corresponds to 10 grain-measures. For metrical weights and measures :— 1. A glass-flask which, when filled to a mark on the neck, contains one litre or 1000 cubic centimetres. 2. A graduated cylindrical jar which, when filled to 0, contains one litre (1000 cubic centimetres), and is divided into 100 equal parts. 3. A burette. A graduated tube which, when filled to 0, holds one litre (100 cubic centimetres), and is divided into 100 equal parts. (One cubic centimetre is the volume of one gramme of Distilled Water at 4«> C=39-28° Fahr.* 1000 cubic centimetres equal one litre.) Volumetric solutions, before being used, should be shaken, in order that they may be throughout of uniform strength. They should also be preserved in stop- pered bottles. All measurements should be made at 60 Fahr. VOLUMETRIC SOLUTION OF BICHEOMATE OF POTASH. (Bichromate of Potash, KO,2Cr03 = 147-5, or K2Cr207 = 295.) Take of Bichromate of Potash, 147'5 grs.; Distilled Water, a sufficiency : put the Bichromate of Potash into the 10,000 grain flask and, having half filled the flask with water, allow the salt to dissolve ; then dilute the solution with more water, until it has the exact bulk of 10,000 grain-measures. 1000 grain measures of this solution contain ^-th of an equivalent in grains (=1475 grains) of Bichromate of Potash and, when added to a solution of Protosalt of Iron acidulated with Hydrochloric Acid, are capable of converting -Jq th of six equivalents of Iron (= 168 grains) from the state of protosalt to that of persalt. Grammes and cubic centimetres may be employed instead of grains and grain-measures, but for convenience x^th of the numbers should be taken. Thus 14-75 grammes of Bichromate of Potash should be made to form 1000 cubic * It is customary to make the measurements with metrical apparatus at 60° Fahr.