Inhaltsangabe
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1847. Excerpt: ... view, as in fact are all the vegetable compounds, they must have an independent origin. Berzelius believes that the red matter is a distinct substance, which he calls erythrophylle. In the leaves also he has detected a fatty substance of a yellow colour, which he calls xanthophyUe, which appears distinct from anthoxanthine. It is this substance, he states, which, uniting with a matter rather blue than green, in the chlorophylle, remains after the removal of that matter, and gives them their yellow colour. There are therefore probably several distinct compounds in the colouring matters of plants. 452. The colours of wood appear to arise from chemical changes after the death of that part so far as physiological functions are concerned. The contact of air generally deepens the colour of wood. The action of the air upon the vegetable juices is often very striking, changing their colour and even their chemical composition. Thus the root of the Madder, the cells of which are filled with a yellowish juice, when wounded becomes reddened; pure oxygen will not effect this--it requires the presence of aqueous vapour. Many of the large Fungi called Boleti, which are naturally white, when wounded turn blue, green or black; in the B. cyanescens a deep indigo. The colourless juice of Euphorbia is rendered opake and white when exposed to air; that of Chelionium yellow. The tannic acid (§ 28.) which many plants contain probably affects the colour of structures considerably at periods long after they have completed their various vital functions. Sect. III. Development Of Light. 453. On this subject little can be said with any certainty. A few cases appear to be supported by good authority. The daughter of Linna:us observed flashes of light emitted by the flower of Tro...
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