THAER'S PUBLICATION or VIEWS. 85 



authority, in a work of deservedly high reputation, for my doctrine 

 of acid soils. This is Thaer's " Principles of Agriculture/ 7 of 

 which the English translation was first published in the United 

 States in 1846, (in Skinner's "Farmers' Library/') and which 

 permitted my earliest access to the work. The portion on humus 

 testifies positively and fully to the existence of acid soils, and also 

 to such results therefrom as I have maintained. At what time 

 these particular and important views of Thaer were first published, 

 docs not appear; though it may be inferred, as almost certain, that 

 it was subsequent to the discovery and early observations of humic 

 acid of Sprengel and Boullay, as stated above in the article quoted 

 from Rennie's publication of 1833. The preface to the translation 

 of Thaer's work states that the original was first published in Ger- 

 many, in successive numbers, from 1810 to 1812. But a work of 

 ihis kind, in every succeeding edition, would undoubtedly receive 

 from its author such additions and alterations as would keep pace 

 with the progress of agricultural and chemical science. In pre- 

 senting the doctrine of acid in soil, Thaer does not claim the im- 

 portant discovery as his own, nor has he ever been quoted as the 

 first discoverer, or even as one among the earlier investigators. 

 Neither does he refer to other names, as authorities (as Rennie 

 has done above), which would naturally have been do'ne if it was 

 then a discovery so recent as to require such authentication. These 

 would be enough reasons for inferring that Thaer's statements 

 on this subject are of date much later than his first edition. There 

 is another strong reason for this position. If he had announced 

 the existence of acid in soils in his earliest edition, il would have 

 been prior to the earliest elaborate and very able works on agri- 

 cultural chemistry, by Davy and Chaptal. It is incredible that 

 both these distinguished investigators should have passed over such 

 evidence, if in existence, and upon such high agricultural authority 

 as Thaer's, without the slightest notice,, and (as before stated) 

 without making any allusion to the .existence of humic or any 

 other vegetable acid as a very general ingredient of soils. Indeed 

 there is direct proof that Thaer's work was a later publication than 

 Chaptal' s, as the latter is quoted from in the former, in the portion 

 entitled " Theory of Soils." For each and all these reasons, it is 

 impossible that Thaer's notice of humic acid could have been as 

 early as his first edition; and very improbable that it should have 

 been as early as Professor Rennie's statement copied above. 



But whatever was their date, the following passages from Thaer 

 offer confirmation of my views of acid soils more full and complete 

 than to be seen in any other author within my observation, and 

 which, therefore, are doubly welcome, as the testimony of so pro- 

 founcl and distinguished an investigator. 



