TINCTURE OF PHENOL-PHTHALEIN.
Take of
| Phenol-phthalein | 1 gram |
| Proof Spirit | 500 grains |
Dissolve. The solution should be colourless.
III.
TEST SOLUTIONS FOR VOLUMETRIC ESTIMATIONS.
The processes for volumetric estimations may be performed either with British or with metric weights and measures, and the solutions are so arranged that they will be of the same strength, and the same indications will be obtained in using them, whichever system is employed, without the necessity of altering any of the figures by which the quantities of the substances tested or of the test solutions required in the process are expressed.
According to the British system, the quantities of the substances to be tested are expressed in grains by weight, whilst the quantities of the test solutions employed in testing are expressed in grain-measures,—the grain-measure being the volume of a grain of distilled water.
According to the metric system, the quantities of the substances to be tested are expressed in grammes by weight, whilst the quantities of the test solutions employed in testing are expressed in cubic centimetres (C.C.),—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 difference in the results, excepting that, by the metric system, all the quantities will be expressed in relation to a weight (the gramme) which is rather more than fifteen (15.432) times as great as the British grain.
