. The life of the plant. Plant physiology. 122 THE LIFE OF THE PLANT white ash drops to the bottom of the jar : this is magnesia, a compound of the metal magnesium and oxygen. I repeat the experiment, sinking the wire this time into a jar of carbonic acid ; it must now procure oxygen for itself by separating it from the carbon, which will then be set free. As a matter of fact the wire does not burn so quietly this time, but crackles as if so many weak explosions were taking place, and black soot is deposited on the walls of the glass vessel. This is the free carbon. Great stores of carbon are
. The life of the plant. Plant physiology. 122 THE LIFE OF THE PLANT white ash drops to the bottom of the jar : this is magnesia, a compound of the metal magnesium and oxygen. I repeat the experiment, sinking the wire this time into a jar of carbonic acid ; it must now procure oxygen for itself by separating it from the carbon, which will then be set free. As a matter of fact the wire does not burn so quietly this time, but crackles as if so many weak explosions were taking place, and black soot is deposited on the walls of the glass vessel. This is the free carbon. Great stores of carbon are therefore always present in the atmosphere though in an invisible form. All water in contact with the air contains carbonic acid, and plants which grow submerged in water are thus able to obtain it. It is by experimenting with the leaves of submerged plants that the interchange of gases between a leaf and its environment is most readily demonstrated. Here are several experiments which can easily be made on any clear sunny morning. Let us gather some leaves and place them while fresh under a glass bell, filled up to the top with water and then inverted in another glass vessel (fig. 34). We fill them in a pail of water in which it is easy to sink both bell and vessel. If we use common water, or still better water through which carbonic acid has been passed, and then set the apparatus in the light, we shall ^^^^-^j/^^s^-^y^ soon notice the lower surface of the ^^^::::= :=:^^ leaves becoming covered with a silvery layer of bubbles. A little later a considerable amount of gas will be accumulated in the upper part of the bell, while the surplus water will be displaced into the outer vessel, as is shown in fig. 34. Let us repeat this experiment with boiled water, or. Fig. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the origin
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectplantph, bookyear1912
