Chemical lecture experiments . r. 2. Calcium oxide as a drying agent.—The affinity of cal-cium oxide for moisture makes this compound an effectivedrying agent for many gases. 363 364 CHEMICAL LECTURE EXPERIMENTS The absorption of moisture from a gas by calcium oxidemay be shown by moistening the interior of a bell-jar byholding it over a hydrogen flame and then placing it on aporcelain plate in the centre of which are a few lumps ofgood quicklime. A second bell-jar may advantageously bemoistened and placed over a plate containing no lime. Ina short time all the moisture on the walls of the bel
Chemical lecture experiments . r. 2. Calcium oxide as a drying agent.—The affinity of cal-cium oxide for moisture makes this compound an effectivedrying agent for many gases. 363 364 CHEMICAL LECTURE EXPERIMENTS The absorption of moisture from a gas by calcium oxidemay be shown by moistening the interior of a bell-jar byholding it over a hydrogen flame and then placing it on aporcelain plate in the centre of which are a few lumps ofgood quicklime. A second bell-jar may advantageously bemoistened and placed over a plate containing no lime. Ina short time all the moisture on the walls of the bell-jarcovering the lime will disappear, while the other jar willremain unchanged (Fig. 76, p. 175). Two 1. bell-jars ; 2 plates ; H flame ; fresh quicklime. 3. Preparation of calcium phosphide. — Phosphorus,when in contact with heated quicklime, forms calcium phos-phide. Five grams of well-dried yellow phosphorus are insertedin a 50 cm. length of combustion tubing, cm. internal €U>Q t£^&^f%S&3g&& Q. K-J ^S f^ bJ O I C-W ^ Fig. 152 diameter, closed at one end. A plug of asbestos is thenintroduced and a 20 cm. length of the tube filled with lumpsof good quicklime (Fig. 152). The tube is so placed over afour-tube burner that the lime may be strongly heated beforeheating the phosphorus. When the lime has become hot, thephosphorus is brought to a boil and the vapor passed over CALCIUM 365 the heated lime. The phosphorus end of the tube should beheated with a Bunsen burner held in the hand, and a plateof sand should be placed beneath the boiling the phosphorus vapor comes in contact with the hot lime,the lime glows and turns black, forming calcium decomposition of the product by wrater is shown inExs. 29, 30, p. 252. 50 cm. length combustion-tubing; plate of sand; 4-tube burner;fresh quicklime ; P. 4. Hydration of anhydrous calcium sulphate. — Whenanhydrous calcium sulphate (plaster of Paris) is mixed withwater, the water combines with the s
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