Home › Alcoholmetry › ALKALIMETRY

ALKALIMETRY

THE THERMOMETER. various appliances are resorted to, by which | Next, exactly neutralize the alkaline solution the outward flow can be instantly arrested, by adding sufficient of the test acid drop by merely by placing the finger or thumb on an drop. If the saturation is complete, it will orifice arranged for the ingress of air. In the illustrations, e denotes the place of egress for b b C -100 90 80 70 60 b C neither turn litmus paper red, nor turmeric paper brown. (See No. 78.) The weight of alkali tested, bears the same relation to its equivalent weight (see No. 80), that the acidimetric divisions of acid used, do to the percentage of alkali sought. Thus:-If we test 100 grains of potash and find it requires 35 acidimetric divisions of test acid to saturate it, we refer to table No. 80, and find that the equivalent of pure potash is 47 grains. Then 100:47 :: 35:16.45.

That is, the sample of potash under examination contains nearly 16+ per cent. of pure potash. (Sce No. 587.) 50 40 30 20 Fig. 1. Fig. 2.

Fig. 3.

Fig. 4. the contained liquid; b, the orifice for the ingress of air, to be stopped by the finger or thumb; in Fig. 2, both orifices are in a hollow movable stopper; in Fig. 4, the air-hole only is in the stopper, a.

Fig. 1 represents Gay Lussac's Pouret.

Fig. 2, Normandy's modification of Schuster's Alkalimeter. Fig. 3, Birck's Alkalimeter.

Fig. 4 is a simple acidimeter, with a stopper fitted to it, having a groove to correspond with the lip, and a vent-hole drilled through it to admit the air.

The Thermometer.

In Fahrenheit's Thermometer, which is universally employed in this country and Great Britain, the freezing point of water is placed at 32°, and the boiling point at 212° and the number of intervening degrees is 180. long been used in Sweden under the name The Centigrade thermometer, which has of Celsius' thermometer, and is now employed on the continent of Europe generally, marks the freezing point at Zero or 0°, and the boiling point at 100°. In Reaumur's thermometer, used in France before the revolution, the freezing point is Zero, and the boiling point 80°.

Degrees below zero are distinguished by prefixing the minus sign, thus-; so that 170 Fahr. represent a temperature of 17 lower than zero, equivalent to 49 degrees These modifications of the simple acidimeter are employed to allow of the test-liquid be- below freezing point. ing added a single drop at a time, which is absolutely necessary during the first part of grade into degrees of Fahrenheit. Mul- 86. To Convert degrees of Centithe process, to prevent undue effervescence, tiply the degrees of Centigrade by 9, and diand consequent danger of loss of the liquid; vide the result by 5:-then add 32. and in the latter part it is equally indispensable in order to attain exact saturation. They equivalent to 30 degrees of Centigrade. dispense with the use of a separate pipette, Thus: to find the degrees of Fahrenheit being, in fact, acidimeters and pipettes combined. 30 degrees Centigrade.

Multiplied by 9 Alkalimetry. of alkalis. The The method of processes used are the same as in acidimetry; only that the unknown quantity sought is an alkali, and the test applied is an acid. The test acid is 1 equivalent (40 grains, see No. 81) of sulphuric acid sp. gr. 1.032 at 60° Fahr.

Divided by 5)270 54 Add 32 - Answer, 86 degrees Fahrenheit. 87. To reduce degrees of Fahrenheit to the corresponding degrees of Centiinserted in an acidimeter (see No. 82) and grade. Reverse the above process-First made up with distilled water to 100 acidimetric divisions .