Elementary botany . low them to dry. The water solution ofcobalt chloride is red. The paper is also red when it is moist,but when it is thoroughly dry it is blue. It is very sensitiveto moisture and the moisture of the air is often sufficient toredden it. Before using dry the paper in an oven or over aflame. 73. Take two bell jars, as shown in fig. 49. Under one placea potted plant, the pot and earth being covered by oiled cover the plant with a fruit jar. To a stake in the pot pin apiece of the dried cobalt paper, and at the same time pin to a 38 PHYSIOLOG y. stake, in another jar co
Elementary botany . low them to dry. The water solution ofcobalt chloride is red. The paper is also red when it is moist,but when it is thoroughly dry it is blue. It is very sensitiveto moisture and the moisture of the air is often sufficient toredden it. Before using dry the paper in an oven or over aflame. 73. Take two bell jars, as shown in fig. 49. Under one placea potted plant, the pot and earth being covered by oiled cover the plant with a fruit jar. To a stake in the pot pin apiece of the dried cobalt paper, and at the same time pin to a 38 PHYSIOLOG y. stake, in another jar covering no plant, another piece of cobaltpaper. They should both be put under the jars at the sametime. In a few moments the paper in the jar with the plant willbegin to redden. In a short while, ten or fifteen minutes, prob-ably, it will be entirely red, while the paper under the other jarwill remain blue, or be only slightly reddened. The water vaporpassing off from the living plant comes in contact with the sensi-. Fig. 48. Fig. 49- Fig. 48.—Water vapor is given off by the leaves when attached to the living condenses into drops of water on the cool surface of the glass covering the plant. Fig. 49.—A good way to show that the water passes off from the leaves in the formof water vapor. tive cobalt chloride in the paper and reddens it before there issufficient vapor present to condense as a film of moisture on thesurface of the jar. 74. Experiment to compare loss of water in a dry and ahumid atmosphere.—We should now compare the escape ofwater from the leaves of a plant covered by a bell jar, as in thelast experiment, with that which takes place when the plant is TRANSPIRA TIOAT. 39 exposed in a normal way in the air of the room or in the do this we should select two plants of the same kind growingin pots, and of approximately the same leaf surface. The pottedplants are placed one each on the arms of a scale. One of theplants is covered in this position wi
Size: 1984px × 1260px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthoratk, bookcentury1900, bookdecade1900, booksubjectbotany
