APPENDIX. 



INTRODUCTORY REMARKS. 



IN the foregoing exposition of theory and practice, it has been 

 the object and effort of the author to embrace whatever seemed 

 necessary for proof or for illustration ; and to omit everything else, 

 lest too much of amplification or digression should weaken rather 

 than strengthen the main positions. Thus it is believed that the 

 foregoing chapters, as argument and proof, serve to establish the 

 series of propositions which were at first advanced and throughout 

 contended for. Still there remained many minor but interesting 

 subjects, more or less intimately connected with the investigation, 

 or serving for more full proof, and which well deserved more ex- 

 tended discussion, and the consideration of those readers who should 

 desire to pursue farther the general object of this essay. These 

 subjects will be treated separately in the different articles of this 

 appendix ; which may be read, it is believed, with both interest and 

 benefit by the more inquiring class of readers ; or may be passed 

 over, by the more cursory and careless, without much detriment to 

 the arguments and facts of the preceding portion and regular body 

 of the work. 



NOTE I. EXTENSION or THE SUBJECT or PAGES 92 97. v 



Additional proof , offered in the production and existence of black 

 waters, of the action of lime in combining vegetable matters with 

 soil. 



Every person who has seen much of the different parts of lower 

 Virginia (to go no farther for examples), must have remarked the 

 dark permanent colour of the waters' of many streams and mill- 

 ponds ; and that others, whether when clear or when turbid, are at 

 all times and entirely without any tinge of this peculiar colouring 

 matter. The waters thus coloured by vegetable matter are more 

 deeply tinted at some times than at others ; but are alwavs strongly 



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