158 CALCAREOUS MANURES-APPENDIX. 



translation of it were in the course of publication at the same time; and the 

 first volumes of the latter were published at Paris, before the latter volumes 

 of the original work had been sent to the press at Stockholm. The sixth 

 volume of the French translation, from which I have translated the follow- 

 ing extract into English, was printed in 1832. It is not known to me whe- 

 ther the original work is in this country [1835.] 



The following passages contain the opinions of Berzelius, and of other 

 chemists, on humin and humic acids, or as called here, gei?ie and geic acid, 

 and which were referred to in the quotation from Rennie, at page 54. It 

 will be left to the reader to decide how far my views of acid soils are sup- 

 ported by these new opinions of chemists, founded upon chemical analyses 

 of the substances in question. It is proper to state that this new doctrine 

 of geic or humic acid has not passed uncontroverted. It is altogether 

 denied by Raspail, a French chemist, and who is a later writer than Ber- 

 zelius. 



This article will offer scarcely any thing of interest to most readers, 

 and is one of those which will be generally passed over. Its substance 

 might indeed have been given more concisely, and perhaps in a more at- 

 tractive form, if my object had been merely to exhibit the opinions now ge- 

 nerally received among scientific men concerning acid in soil. But it was 

 also designed to exhibit what was the utmost possible extent of scientific 

 authority for this doctrine, so far as could have been known in this country 

 when the last preceding edition of this essay was published in 1835. When 

 my still earlier editions asserted the same doctrine, as then and now, there 

 was not only no scientific authority for acid in soil, but all authority was 

 opposed, either directly or indirectly. 



[translation.] 



Products of putrefaction at the surface of the earth. 



Mould (terreau.)— The vegetable matters which rot at the surface of the 

 earth, finish by leaving a blackish brown pulverulent mass, which has re- 

 ceived the name of mould [humus.] 



All the vegetation of a year, which dies at the arrival of winter, is con- 

 verted by degrees to mould, which is mixed with the earth in which the 

 plant grew ; whence it comes that the extreme surface of the earth con- 

 tains a greater or less proportion of mould, which serves for the nutriment 

 of the succeeding growth of plants. This mould, such as it is found in 

 the earth, is often mingled with the products of a less advanced putrefac- 

 tion, or even with vegetable parts not changed, principally a great quantity 

 of small roots. If we examine the mould, such as it is found in cultivated 

 soils, it is found to be in a mass very much mixed ; but it is always pos- 

 sible to extract the parts which characterize mould. 



During the transformation of the vegetable matters to mould, the first 

 portion of their mass is changed into a brownish black substance, which 

 presents all the characters of apotheme* when we have separated from it 

 the unaltered extract, which the apotheme draws with it. The salts of 

 such acids as are of organic origin, contained in the vegetable matter, are 

 destroyed, so that the elements of the acid are resolved into water and 

 carbonic acid, whilst the base is combined with the substance analogous 



* What Berzelius calls apotheme is " a deposite slightly soluble in water, produced 

 in an aqueous solution of vegetable extract during slow evaporation, and containing a 

 larger proportion of carbon, than does an equal weight of extract," 



