. Elementary physics and chemistry: second stage. Science. MOISTURE IN THE AIR. 23 Strong sulphuric acid should be handled with great care. What to do. Repeat the experiments on condensation in the last lesson. Moisture taken from the air by calcium cJiloride.—Place some lumps of dry white calcium chloride in a basin, and find the mass of the basin and its contents. Expose the calcium chloride to the air for two or three hours. Notice the solid has disappeared and a liquid is present in its place. Find the mass of the basin and liquid ; you will fin,d it greater than before. The increase shows
. Elementary physics and chemistry: second stage. Science. MOISTURE IN THE AIR. 23 Strong sulphuric acid should be handled with great care. What to do. Repeat the experiments on condensation in the last lesson. Moisture taken from the air by calcium cJiloride.—Place some lumps of dry white calcium chloride in a basin, and find the mass of the basin and its contents. Expose the calcium chloride to the air for two or three hours. Notice the solid has disappeared and a liquid is present in its place. Find the mass of the basin and liquid ; you will fin,d it greater than before. The increase shows the mass of the water taken out of the atmosphere by the calcium chloride. Moisture taken from the air by sulphii7-ic acid.— Repeat the last experiment,. SULPHURIC ACID AMD MOISTURE FROM substituting a small wide- the air mouthed bottle for the F"^- 19.—when sulphuric acid IS exposed , . J .to the air for a few days it absorbs so basm, and strong sulphuric much moisture that a rise of level is pro- acid for the calcium chlor- '^"<^^'^- ide. Leave the acid exposed for a day, and, as before, notice the increase of mass. Weigh again after a second day's exposure and notice the further increase of mass. REASONS AND RESULTS. There is always -water vapour in the air.—Since, as was learnt in the last lesson, evaporation is always going on from every surface of water, whether it be that of sea, lake, or river, there must always be some water vapour present in the air. The amount on hot days is greater than on cold ones, because the warmer the air the larger the amount of moisture it can take up. For this reason clothes usually dry more quickly on hot than on cold days. When describing condensation, some of the ways in which the presence of this water vapour can be shown were explained. Whenever a cold surface comes into contact with warm air, the water vapour which the air contains is deposited in the form of visible moisture. Some substances take water vapour out
Size: 2034px × 1229px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectscience, bookyear1900
