Observations on Liebig^s " Organic Chemistry." 115 



saturation of an acid is constant. As these acids and bases, and 

 even the form they present themselves in, are not subject to 

 change; it may be affirmed, he says, that they exercise an im- 

 portant influence in the developement of fruits and seeds, and 

 also in many other formations, of the nature of which we are yet 

 ignorant. If the acid is required for the organs, the alkaline 

 base must be present; it may be altered from soda to potash, as 

 in the Salsola Kdli^ grown from seeds of plants ripened at a 

 distance from the sea ; or the alkali may be lime, but some base 

 must be present. Potatoes grown in cellars without earth 

 furnish a true alkali called solanin, of a very poisonous nature, 

 in the sprouts, which they never do in the fields. This ne- 

 cessity for an alkali, he thinks, shows that alkaline bases are 

 connected with the developement of plants. The meconic acid 

 in poppies is united with the alkaloids narcotina, morphia, 

 codeia, &c. : the bases may vary, but the quantity does not; 

 when there is a deficiency in meconic acid, it is made up by the 

 sulphuric acid, the proportions being always the same. 



If inorganic acids, he says, are thus substituted at times for or- 

 ganic, the substitution of the inorganic alkalies for the organic is 

 likely to take place in a much higher degree. When roots find 

 their more appropriate bases or alkalies in sufficient quantity, they 

 will take up less of another. When the soil in which a white 

 hyacinth is growing in flower is sprinkled with the juice of the 

 Phytolacca decandra, the blossom, he says, will assume in one 

 or two hours a red colour, which the influence of sunshine will 

 cause to become gradually white again after a few days; the 

 juice will either be excreted entire, or, if any of its elements are 

 nutritious to the plant, the remainder will be separated. Acetate 

 of lead, and nitrate of strontian, absorbed by plants in the ex- 

 periments of Macaire Prinsep, were returned again by the root 

 as excrement: thus, he says, soil where common salt abounds 

 will return it though absorbed ; it will also kill the plant if in 

 excess, and so would acetate of lead. 



Firs and pines, he says, have but little alkali in their ashes. 

 Lime trees, rye, and potatoes have much more ; and firs will 

 thrive in quantities on barren sandy soils, while wheat and lime 

 trees will not. The spruce fir, however, will not thrive on a dry 

 soil, however alkaline it may be ; and the state of moisture of the 

 soil must, therefore, have its share as well as alkalies. All kinds 

 of grasses, and also ^quisetacese, contain a large quantity of 

 silex in the stalks and outer parts of the leaves, in the form of 

 siUcic acid, or oxide of silicon (the form silex is generally found 

 in) and potash united, forming silicate of potash. This is mostly 

 returned to the cultivated grasses, in the form of rotted straw, in 

 the manure. In natural meadows, he says, where the hay is 

 taken off, we never find a luxuriant crop of grass on sandy 



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