S3 



AGRICULTURAL CHEMISTRY. 



Carbonate of Potash 7'36 

 Lime 51*19 



Magnesia 0000 



Sum of the carbonates 58*55 



Quantity of oxygen in the Potash 0'85 



" Lime ,8'10 



Sum of the oxygen in the bases 8'95 



The numbers 9'01 and 8*95 resemble each 

 other as nearly as could be expected even 

 in analyses made for the very purpose of 

 ascertaining the fact above demonstrated 

 which the analyst in this case had not in 

 view. 



Let us now compare Berthier's analyses 

 of the ashes of two fir-trees, one of which 

 grew in Norway, the other in Allevard (de- 

 partement de 1'isere). One contained 50, the 

 other 25 per cent, of soluble salts. A greater 

 difference in the proportion of the alkaline 

 bases could scarcely exist between two to- 

 tally different plants, and yet even here the 

 quantity of oxygen in the bases of both was 

 the same. 



100 parts of the ashes of firwood from 

 Allevard contained, according to Berthier, 

 (Ann. de Chim. et de Phys. t. xxxii. p. 

 248,) 



Potash & Soda 16'8 in which 3'42 must be oxygen. 

 Lime . 29'5 8.20 " 

 Magnesia 3'2 " 1.20 " " 



49.5 



12-82 



Only part of the potash and soda in these 

 ashes was in combination with organic 

 acids ; the remainder was in the form of 

 sulphates, phosphates, and chlorides. One 

 nundred parts of the ashes contain 3-1 sul- 

 pnunc acid, 4-2 phosphoric acid, and 0-3 

 hydrochloric acid, which together neutralize 

 a quantity of base containing 1-20 oxygen. 

 This number therefore must be substracted 

 from 12-82. The remainder 11-62 indicates 

 the quantity of oxygen in the alkaline 

 bases, combined with organic acids in the 

 firwood of Allevard. 



The firwood of Norway contained in 100 

 parts, * 



Potash 

 Soda 

 Lime 

 Magnesia 



14'1 of which 2-4 would be oxygen. 

 207 " 5-3 " 



123 " 3'45 " " 



4-35 " 1-69 " " 



51-45 



12-84 



And if the quantity of oxygen of the 

 bases in combination with sulphuric and 

 phosphoric acid, viz. 1-37, be again sub- 

 stracted from 12-84, 11-47 parts remain as 

 the amount of oxygen contained in the bases 

 which were in combination with organic 

 acids. 



* This calculation is exact only in thfi case 

 where the quantity of ashes is equal in weight for 

 a given quantity of wood ; the difference cannot, 

 however, be admitted to he so great as to change 

 sensibly the above proportions Berthier has not 

 mentioned the proportion of ashes contained in 

 Ihe wood. 



These remarkable approximations cannot 

 be accidental ; and if further examinations 

 confirm them in other kinds of plants, no 

 other explanation than that already given 

 can be adopted. 



It is not known in what form silica, man 

 ganese, and oxide of iron, are contained in 

 plants; but we are certain that potash, soda, 

 and magnesia, can be extracted from all 

 parts of their structure in the form of salts 

 of organic acids. The same is the case with 

 lime, when not present as insoluble oxalate 

 of lime. It must here be remembered, that 

 in plants yielding oxalic acid, the acid and 

 potash never exist in the form of a neutral 

 or quadruple salt, but always as a double 

 acid salt, on whatever soil they may grow. 

 The potash in grapes also is more frequently 

 found as an acid salt, viz. cream of tartar, 

 (bitartrate of potash,) than in the form of a 

 neutral compound. As these acids and 

 bases are never absent from plants, and as 

 even the form in which they present them- 

 selves is not subject to change, it may be 

 affirmed that they exercise an important in- 

 fluence on the developement of the fruits and 

 seeds, and also on many other functions of 

 the nature of which we are at present igno- 

 rant. 



The quantity of alkaline bases existing in 

 a plant also depends evidently on this cir- 

 cumstance of their existing only in the form 

 of acid salts, for the capacity of saturation 

 of an acid is constant ; and when we see 

 oxalate of lime in the lichens occupying the 

 place of woody fibre which is absent, we 

 must regard it as certain that the soluble or- 

 ganic salts are destined to fulfil equally im- 

 portant though different functions, so much 

 so that we could not conceive the complete 

 developement of a plant without their pre- 

 sence, that is, without the presence of their 

 acids, and consequently of their bases. 



From these considerations we must per- 

 ceive, that exact and trustworthy examina- 

 tions of the ashes of plants of the same kind 

 growing upon different soils would be of the 

 greatest importance to vegetable physiology 

 and would decide whether the facts above 

 mentioned are the results of an unchanging 

 law for each family of plants, and whether 

 an invariable number can be found to ex- 

 press the quantity of oxygen which each 

 species of plant contains in the bases united 

 with organic acids. In all probability such 

 inquiries will lead to most important results; 

 for it is clear that if the \ reduction of a cer- 

 tain unchanging quantity of an organic acid 

 is required by^the peculiar nature of the 

 organs of a plant, and is necessary to its ex- 

 istence, then potash or lime must be taken 

 up by it in order to form salts with this acid ; 

 that if these do not exist in sufficient quan- 

 titv in the soil, other bases must supply their 

 place; and that the progress of a plant must 

 be wholly arrested when none are present. 



Seeds f the Salsola Kali, when sown in 

 common garden soil, produce a plant con- 

 aining both potash and soda; while the 



