Science for beginners . aturated with dissolved air; it containsall the air it is possible for it to contain under the given con-ditions. From Ex. 77 what do you conclude is the effectof reducing the pressure of the air upon the surface of thewater ? 412 WATER SUPPLY AND SEWAGE DISPOSAL Henrys Law.—The amount of gas dissolved in water isdirectly proportional to the pressure, that is, doubling the pres-sure doubles the amount of gas which dissolves in a givenquantity of water. This law holds true only when there is nochemical union between the gas and water, as is the case whenair is dissolved
Science for beginners . aturated with dissolved air; it containsall the air it is possible for it to contain under the given con-ditions. From Ex. 77 what do you conclude is the effectof reducing the pressure of the air upon the surface of thewater ? 412 WATER SUPPLY AND SEWAGE DISPOSAL Henrys Law.—The amount of gas dissolved in water isdirectly proportional to the pressure, that is, doubling the pres-sure doubles the amount of gas which dissolves in a givenquantity of water. This law holds true only when there is nochemical union between the gas and water, as is the case whenair is dissolved in water. One cu. ft., or 1728 cu. in., of water at 0°C. and at thepressure of 15 lb. per sq. in., that which the atmosphereexerts at the sea level, dissolves about 45 cu. in. of air. ByHenrys Law we see that doubling this pressure would causeabout 90 cu. in. of air to be dissolved in each cubic foot ofwater, or reducing the pressure to 5 lb. to the sq. in. reducesthe amount of dissolved air to 15 cu. in. per cu. Fig. 244.—Why shallow wells are dangerous. The need of pumping more air into the tank occasionallyto prevent it from becoming water-logged is now water in the well or cistern is under 1 atmosphere ofpressure; therefore there are about 45 cu. in. of air in solu-tion to each cubic foot of water as it enters the tank. Thewater in the tank is kept constantly under a pressure of, atleast, 2 atmospheres; the water, therefore, as it escapes fromthe tank through the pipes and faucets, contains at least twice WATER SUPPLY FOR FARMHOUSE AND COUNTRY HOME 413 as much, air as it did in the well. Evidently, if no additionalair were pumped into the tank, the tank would soon becomewater-logged. What would be the result? 488. Shallow Well Water Often Dangerous.—We haveseen that wells are supplied by the ground-water. It is evi-dent that, if the walls of the well are merely bricked up toprevent the walls from caving in, they will not be water such cases
Size: 2222px × 1125px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectscience, bookyear1921
