118 



HISTORY OF THE VEGETABLE KINGDOM. 



when the ashes are abundant. An 100 parts 

 of mould furnished by combustion 50 parts of 

 ashes which did not give out their salts to 

 boiling water. But 100 parts only of dried 

 extract from the same mould, yielded only 

 14 parts of ashes ; and 100 parts of the ashes 

 foi-med with boiling water, a ley wliich con- 

 tained 25 parts composed of potash in an un- 

 combined state, and of allvaline sulphates and 

 muriates; and yet, upon further analysis, it was 

 found that the water had not extracted more 

 than one half of the salts wliich the ashes con- 

 tained. The soil, tlierefore, contains an abun- 

 dant supply of salts for all the purposes of vege- 

 tation. It may even in some cases, contain too 

 much; for it is to be recollected that saline sub- 

 stances are beneficial to vegetation only when 

 applied in very small qiiantities. If they are 

 administered in great abundance they destroy 

 the plant. 



And the argument against their utility that 

 has been drawn from the small proportion in 

 which they are found to exist in the plant itself, 

 is altogether inadmissible; because it is very 

 well known that some pai'ticular ingredient may 

 be essential to the composition of a body, and 

 yet constitute but a very small proportion of its 

 mass. Atmospheric air contains only about one 

 part in the 100th of carbonic acid ; and yet no 

 one will venture to affirm that carbonic acid gas 

 is merely an adventitious and accidental element, 

 existing by chance, in the air of the atmosphere, 

 and not an essential ingredient in its composi- 

 tion. Phosphate of lime constitutes but a very 

 small proportion of animal bodies, perhaps not 

 one part in 600; and yet no one doubts that it is 

 essential to the composition of the bones. But 

 the same salt is found in the ashes of all vege- 

 tables ; and who will say that it is not essential 

 to their perfection? 



Earths. As most plants have been found by 

 analysis to contain a portion of alkaline or earthy 

 salts, so most plants have been found to contain 

 also a portion of earths: and as the two sub- 

 stances are so nearly related, and so foreign in 

 their character to vegetable substances in general, 

 the same inquiry has consequently been made 

 with regard to their origin. Whence are the 

 earths derived that have been found to exist in 

 ])lants? 



It seems to have been the opinion of Lampa- 

 dius, that the earths contained in plants are 

 merely the effect of vegetation, and altogether 

 independent of the soil in which they grow: 

 and extravagant as the opinion is, it has been 

 made to assume the semblance of resting upon 

 experiment. Lampadius prepared, in his garden, 

 five small beds of four feet square in surface by 

 one in depth; each bed consisted of a pure earth 

 mixed with eight pounds of cow-dung. The 

 earths were alumine, silica, lime, magnesia, and 



garden mould. They were sown with rye, and 

 the produce of each was separately reduced to 

 ashes. But the same principles were found in 

 them all; amongst which was a portion of silica; 

 whence Lampadius concluded, that the silica 

 found in plants is merely the result of vegeta- 

 tion, having no relation whatever to the soil in 

 which the plants grow. 



But this conclusion was by much too hasty, 

 and has been since shown to be most palpably 

 eiToneous ; because Lampadius does not take into 

 the calculation the constituent principles of the 

 cow-dung with which his earths were mixed, the 

 very substance from which his plants must have 

 derived the greater part of their nourishment. If 

 this precaution had been taken, his conclusion 

 must have been very different : for it has been 

 ascertained by Ruckert, that dung does actually 

 contain a portion of silica ; which, in the case 

 of cow-dung, will appear the less surprising if 

 it is only recollected that the plants which cowa 

 principally feed on, do themselves contain a por- 

 tion of silica. To the cow-dung, therefore, with 

 which the different earths were manured, the 

 origin of silica may be traced. It was thus of 

 necessity found in them all, though not per- 

 haps in an equal proportion. 



Saussure, in adverting to the experiment of 

 Lampadius, exposes indeed, the absurdity of hig 

 conclusion ; but deduces from it another which 

 is perhaps equally exceptionable, namely, that 

 plants growing in calcareous and granitic sand, 

 mixed v^ith the same manure or mould, will 

 produce equal quantities of ashes. But this 

 supposes manures to have the same action upon 

 all soils, wliich is surely not the fact : and if 

 there be any manure that acts on a calcareous 

 soil, without acting at all on a granitic soil, then 

 the quantity of ashes will be altered in the for- 

 mer case, from that very circumstance; because 

 the plant is now nourished not only by the 

 manure that was committed to the soil, but from 

 the original soil itself, in its state of combina- 

 tion with the manure. 



The Berlin academy proposed as a prize ques- 

 tion, " to determine the earthy constituents of 

 tlie different kinds of corn, and to ascertain 

 whether these earthy parts are formed by the 

 process of vegetation. The prize was gained by 

 Schrader of Berlin. He analyzed the seeds of 

 wheat, rye, barley, and oats, and ascertained the 

 portion of earth which each contains. He ana- 

 lyzed, in the same manner, rye straw; and hav- 

 ing in this way ascertained the proportion of 

 earth \\'hich these seeds contained, he endeavoured 

 to make them grow in some medium, which could 

 not furnish any earthy ingredient whatever. 

 For a long time his attempts were baffled; every 

 substance tried containing less or more of earth, 

 and being therefore improper. At last he found 

 that flowers of sulphur might be used with 



