SALT* 



stances (for instance, with the various 

 line matters draining from a dunghill), that 

 thru every difficulty is removed. Neither must 

 tht cultivator suppose, that when saline sub- 

 stances are mixed with the soil, that then the 

 plant growing upon it absorbs those salts as a 

 matter of necessity, united with the moisture 

 contained in that soil, without having the power 

 of rejecting or separating it from its solution ; 

 for foch aa assumption has been proved to be 

 contrary to the fact by several very accurate 

 experiments. M. Saussure, for instance, found 

 thai plant* had the power, when placed in sa- 

 reign to their habits, of sepa- 

 rating them from the water in which they were 

 di*M>lvcd. These are researches fraught with 

 instruction to the cultivator. He dissolved the 

 ollowing salts in water, in such proportions 

 hat each solution contained T | ff part of its 

 weight of the salt muriate of potash, muriate 

 of soda (common salt), nitrate of lime, sul- 

 phate of soda (Glauber salt), muriate of am- 

 monia (sal ammonia), acetate of lime, sulphate 

 of copper (blue vitriol). In each of these so- 

 lutions he put plants of Polygonvm Persicaria 

 or of Ihdfnt rann<i6iiia, furnished with their 

 roots. The Polypotntm grew for five weeks in 

 the solution of muriate of potash, nitrate of 

 muriate of soda, and sulphate of soda, 

 and its roots increased in them as usual. It 

 lan*uishr.l in the solution of sal ammoniac, 

 aad the roots made no progress. It died in 8 

 or 9 days in the solution of acetate of lime, 

 and in less than 3 days in the solution of sul- 

 phate of copper. When such a number of 

 plant* of Polygon* were put into the solu- 

 tions as to absorb one-half oi each in 2 days, 

 the remaining half was found to have lost very 

 t proportions of the salt which it had 

 originally contained. Supposing the portion 

 of salt at first in solution to be 100, the follow- 



SALTS. 



fi C Nitrate of lime 

 t Sulphate of copper 

 f Sulphate of soda - 



7. < Muriate of soda 

 (.Acetate of lime 



Parto. 

 17 

 34 

 6 

 10 

 



ing table exhibits the quantity of each which 

 nad disappeared when one-half of the liquid 

 waa absorbed 



M.rt.teorpota.h - . . . Jp 

 Muriate of oda .... 



Nitrate of lime 4 



talphaie of oda .... 14-4 



Mnriaie of ammonia - - - - 12 



Acetate of lime g 



ulphate of copper .... 47 



The tod,*, absorbed pretty nearly the same 

 it in general did not vegetate so 



I : --' ' - M /' V" 'in/);). 



irhea various salts were dissolved at once 

 1 ame solution, and plants made to vege- 

 tate m them, it was found that different propor- 

 oii* of the salts were absorbed. The follow- 

 mg table exhibits the results of these trials 

 mg, as before, the original weight of 

 ich salt to have been 100, each solution con- 

 tained T I, pan of its weight of each salt 



. 



11-7 

 22 

 13 

 17 



4-5 

 16-5 

 31 

 34 



8 

 17 



These experiments succeeded nearly equally 

 with other plants, as the Mentha piperita and 

 the Scotch fir. When the roots were cut. or 

 removed, the plants absorbed all solutions in- 

 discriminately; on examining the plants, the 

 salts absorbed were found in them unaltered. 

 It being thus clearly established that plants 

 possess a discriminating power, and that they 

 do not absorb saline solutions merely because 

 they happen to be dissolved in the soil, it next 

 becomes an object of interest, as an illustra- 

 tion and guide for the operations of agricul- 

 ture, to ascertain what salts are found by the 

 researches of the chemist in commonly culti- 

 vated plants. And if, at the conclusion of our 

 examination, we find that certain salts are 

 found in abundance only in certain plants, and 

 that these saline substances exist, in them in- 

 variably in all soils and situations, and that 

 without their presence the plant languishes and 

 merely supports a sickly existence, we shall 

 be almost driven to the conclusion, that these 

 are as essentially the food of plants, as any of 

 the other substances with which they abound. 

 For a lengthened period, the vegetable alka- 

 line salt, carbonate of potash, has been ob- 

 tained from plants. Procured at first by their 

 combustion, in iron pots, it hence obtained its 

 name. Dr. Thomson has given a table of the 

 quantity of potash obtained from 100 parts of 

 the ashes of various trees and plants. See 

 ALKALI. 



In general, says Dr. Thomson, three times as 

 much ashes are obtained from shrubs as from 

 trees. An equal weight of the branches of 

 trees produce more ashes than the trunk, and 

 the leaves more than the branches. Herbs ar- 

 rived at maturity produce more ashes than at 

 any other time. Green vegetables produce 

 more ashes than dry. The salt which is ob- 

 tained by the combustion of plant;,, although 

 chiefly composed, does not consist wholly of 

 potash: there are many salts mixed with it; 

 these are usually sulphate of potash, muriate 

 of potash, sulphate of lime, phosphate of lime, 

 &c., but these bear in general but a small pro- 

 portion to the potash. 



Perhaps the most copious table of the alka- 

 line and other salts obtained by the combus- 

 tion of various plants has been given by M. 

 Saussure in his chemical researches on vege- 

 tation. He obtained from 100 parts of the 

 ashes of the 



Leaves of oak (Quercus Robur), May 10 



Do., September 27 .... 

 Wood of a young oak, May 10 

 Bark of do. ---._. 

 Perfect wood of oak - 

 Albumen of do. ... 



Bark of do 



Cortical layers of do. .... 

 Extract of wood of do. - 

 Soil from the wood of do. - 

 Extract from do. - .... 

 Leaves of poplar (Populus nio-rd), May 10 



Do., September 12 . ... 

 Leaves of hazel - 



Do., washed in cold water ... 

 Leaves of do., June 22 . 



Do., September 20 .... 



'J? * 

 17. 



7- 

 7- 



7- 



r 



51- 

 24- 

 66- 

 36- 

 26- 

 26- 

 8-2 

 22-7 

 11- 



