THE ASH OF PLANTS. 177 



dental also, or in excess above what is really needed by 

 the plant, and leaves us to infer that the quantity of 

 these bodies absorbed, depends to some extent on the com- 

 position of the soil, and is to the same degree independent 

 of the "wants of vegetation. 



Alkalies in Strand and Marine Plants. — The above 

 conclusions cannot as yet be accepted in case of plants 

 which grow only near or in salt water. Asparagus, the 

 beet and carrot, though native to saline shores, are easily 

 capable of inland cultivation, and indeed grow wild in 

 total or comparative absence of soda-compounds.* 



The common saltworts, Salsola, and the samphire, Sali- 

 cornia, are plants, which, unlike those just mentioned, 

 never stray inland. Gobel, who has analyzed these plants 

 as occurring on the Caspian steppes, found in the soluble 

 part of the ash of the Salsola hrachiata, 4.8 per cent of 

 potash, and 30.3 per cent of soda, and in the Salicornia 

 heriacea, 2.6 per cent of potash and 36.4 per cent of soda; 

 the soda constituting in the first instance no less than '|jj, 

 and in the latter '1^^ of the entire weight, not of the ash, 

 but of the air-dry plant. Potash is never absent in these 

 forms of vegetation. {Agricultur-Chemie, ote Aiif., p. 66.) 



According to Cadet, {Liehig's Erndlwung der Veg., p. 

 100,) the seeds of the Salsola kali, sown in common garden 

 soil, 'gave a plant which contained both soda and potash ; 

 from the seeds of this, sown also in garden soil, grew plants 

 in which only potash-salts with traces of soda could be 

 found. 



Another class of plants — the sea-weeds, (algae,) — derive 

 their nutriment exclusively from the sea-water in which 

 they are immersed. Though the quantity of potash in sea- 

 water is but 'Ijj that of the soda, it is yet a fact, as shown 

 by the analyses of Forchhammer, {Jburfiir Fralct. Chem., 



* TMs is not, Indeecl, proved by analysis, in case of the carrot, but is doubt- 

 less true. 



8* 



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