. A companion to Blackie's tropical readers, books I and II : containing suggestions for experiemnts and practical work . and shake. Amilky precipitate will be noticed. Expt. 194. Where the Water Vapour in the Airconies from. (a) Plants.—Tie a wide-mouthed bottle on to a branchof a guango tree, and observe that water condenses in-side. The mouth of the bottle should be closed. (b) Animals.—Breathe against a piece of glass, andobserve the moisture deposited. (c) Water Surfaces.—Observe how water exposed in asaucer evaporates into the air. In a similar way waterin the sea, rivers, ponds, &c, is
. A companion to Blackie's tropical readers, books I and II : containing suggestions for experiemnts and practical work . and shake. Amilky precipitate will be noticed. Expt. 194. Where the Water Vapour in the Airconies from. (a) Plants.—Tie a wide-mouthed bottle on to a branchof a guango tree, and observe that water condenses in-side. The mouth of the bottle should be closed. (b) Animals.—Breathe against a piece of glass, andobserve the moisture deposited. (c) Water Surfaces.—Observe how water exposed in asaucer evaporates into the air. In a similar way waterin the sea, rivers, ponds, &c, is always passing ofl intothe air in the form of vapour. WHY THE WIND BLOWS (See Tropical Readers, Book II, pp. 169-171.) Expt. 195. Air expands whenHeated.—Fit up a flask as shown infig. 32; heat gently, and observe thatthe hot air expands as shown by therising of the drop of water. Expt. 196. Warm Air rises.—Putlight bits of paper or small feathersabove a fire, in a chimney for example,and observe how they rise with thewarm air. Expt. 197. How a Balloon may bemade.—Make a balloon about 2 ft. in (C282). Fig. 32.—Expansionof Air when heated 6 82 COMPANION TO TROPICAL READERS diameter by pasting paper over a very light framework;put two fine wires crossing one another at the openingat the bottom; tie a sponge where the wires meet, andsaturate it with alcohol; set fire to the sponge and theballoon will rise. This experiment should only be doneby the teacher. Expt. 198. Soil both absorbs and gives out Heatmore quickly than Water.—Heat at the same timeover the same fire a tin filled with soil and anotherof equal size filled with water, for five to ten minutes;observe which gets hotter. Allow both to cool, andobserve which cools first, remembering that the soil wasthe hotter. VENTILATION (See Tropical Readers, Book II, pp. 171-174.) Expt. 199. A well-ventilated Building.—Write adescription of any building that you consider well ven-tilated. Expt. 200. A badly-ventilat
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