CALCAREOUS MANURES -APPENDIX. 177 



times with suspended clay and mud, are never colored by vegetable ex- 

 tractive or soluble matter alone. 



If we go farther for examples, the effects will be found to be still more 

 striking. None of the lime-stone streams are ever colored ; and their re- 

 markable transparency, very far surpassing that of the most pure and 

 limpid waters of the low country, show that the dissolved lime, which the 

 mountain streams contaiii, serves to remove every thing of coloring matter. 

 These lime-stone waters, and land floods from rains which also necessarily 

 carry dissolved carbonate of lime, form the principal supply of the upper 

 James river. But long before the waters reach the head of tide, not a 

 particle of lime remains. The dissolved lime had been continually uniting 

 with the suspended or dissolved vegetable matter, until no lime was 

 left, and the precipitated compound had served to add more manure to the 

 extensive low-grounds along the whole course of the upper James river, 

 and which are so well known and deservedly celebrated for their great 

 and enduring fertility and high value. 



When a resident of the lower country first visits our mountain and 

 lime-stone region, he cannot avoid observing and being forcibly impressed 

 by the remarkable clearness of the waters. Pools and basins in the 

 streams containing six feet depth of water, will appear to his unprac- 

 tised eye as not deeper than two or three feet. And it is only by com- 

 parison, and by becoming acquainted with this really and perfectly clear 

 lime-stone water, he learns that he had, in truth, never before seen a stream 

 or pond of perfectly clear water. Though the dissolved matters may be 

 in too small quantity to produce any appearance of color, they serve to 

 impair the transparency of the water. And when any such coloring or 

 vegetable matters are received into and intermixed with lime-stone streams, 

 the vegetable matter is immediately combined with lime, and the compound 

 precipitated ; still leaving in the water a great excess of dissolved lime, 

 scarcely diminished by the loss of the small part acting to clear the water 

 of all coloring and vegetable impregnation. 



From the large proportion of lime held in solution by lime-stone springs, 

 and the streams proceeding from them, and also by rain floods passing 

 over lime-stone soils, it must be inferred, (according to my views,) that such 

 waters must very quickly combine with and precipitate all coloring matters, 

 and, when not turbid with earthy matter, be as transparent as water can 

 possibly be. Hence, the well known and remarkable transparency of such 

 water is not directly caused (as commonly understood) by lime be- 

 ing contained in them — but because of the other adulterations being 

 totally removed in combination with a part of that dissolved lime. Thus, 

 the water is not in the least made crystalline and transparent because of 

 what it contains, but because of what it has been deprived of. And, there- 

 fore, even after all the lime may have been precipitated, the water must 

 retain its previous perfect transparency, unless subsequently impregnated 

 with other coloring matter. 



The additional supply of carbonic acid to water, which alone gives to it 

 the power to dissolve or to retain in solution even the smallest proportion of 

 carbonate of lime, is not strongly held. It is given off by the lime-stone 

 water in its partial evaporation, and to every contact of atmospheric air ; 

 and this operation is increased by such agitation of the water as exposes 

 a larger surface to the air. Hence, at all rapids of lime-stone streams, 

 there is a peculiarly rapid and large deposition of carbonate of lime, let 

 loose by the water because of the loss of the proportion of carbonic acid 

 which before served to hold the lime dissolved in the water. This pre- 

 cipitation and gradual accumulation of carbonate of lime, at the rapids and 



