[Frost and fire : natural engines, tool-marks and chips : with sketches taken at home and abroad by a traveller] . ottom ; at the opposite corner the stalk of a ther-mometer is thrust through a bung, and so placed that it canbe raised or sunk without disturbing the water much. Thinice formed in the tank floats at the surface, and a block-tinbottle filled with hot water is sunk. The heat of the waterput into the bottle is 212°, the ice is 32°, On the ice, aboutthe centre of the tank, some lamp black is painted on witha brush, one side of the tank is covered with a screen of thinpaper, and then
[Frost and fire : natural engines, tool-marks and chips : with sketches taken at home and abroad by a traveller] . ottom ; at the opposite corner the stalk of a ther-mometer is thrust through a bung, and so placed that it canbe raised or sunk without disturbing the water much. Thinice formed in the tank floats at the surface, and a block-tinbottle filled with hot water is sunk. The heat of the waterput into the bottle is 212°, the ice is 32°, On the ice, aboutthe centre of the tank, some lamp black is painted on witha brush, one side of the tank is covered with a screen of thinpaper, and then the machine is ready for action. As the colour is at the coldest place :—on the ice, it marksthe position of the coldest water when tlie ice begins to melt, WATER. 75 and the cold is easily measured with the instruments. As thehot bottle is in clear water, white paper seen through clearwater marks the position of the water which is warmed. Aslamp black takes many days to settle in a tumbler, it shewsthe movements of water, for it only moves al)out the tank,because water is moved by weight and Fig. Freezing. Ice being at the top is lightest, and its temperature is 32°.WTien it is melting the colour begins to move. If it is warmedby the sun, a dark revolving column sinks very slowly beneath the ice are layers which contain intricate patternsof curved lines of black, which bend and wave slowly, butkeep near the ice. The temperature in the coloured band isIce, 32°Water, 33°34°37 As shewn in the woodcut. 76 WATER. So the coldest of these layers is the lightest, and the solidcrust is lightest of all. The clear water in contact with thecoloured layer is at 40°, and so is the water elsewhere in thetank, after the hot bottle has given off its charge of heat andmelted the equivalent weight of ice. So water at 40° isheavier than water at 37°, and the different temperatures aredrawn in black on a white ground. But water that is warmerthan 40° is ligh
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Keywords: ., bookpublisheredinburghsn, booksubjectgeo, booksubjectmeteorology
