140 CALCAREOUS MANURES— PRACTICE. 



Dr. Braxton's total expense, the transportation being for eight miles on the 

 narrow and smooth Pamunkey, was but little more than half a cent the 

 bushel, placed at his landing. No charge was made for the marl in either 

 case, but every other charge or expense was included. The labor and 

 difficulties on James river, both of uncovering and digging the marl 

 (at Coggins Point) and unloading (on a shallow creek) were unusually 

 great ; and on the Pamunkey these labors were very light. A vessel and 

 also a mode of loading, safe in strong winds, were necessary on James 

 river ; while no such danger had to be feared, or was guarded against, on 

 the well sheltered Pamunkey river. So much of the business in both these 

 cases, as was conducted from home, necessarily was wanting of proper 

 superintendence ; and, no doubt, both of these undertakings suffered for 

 that important deficiency, as in all cases where labor is on a small scale of 

 operations, and more especially when slave labor is employed. 



CHAPTER XV. 



THE USB OF CALCAREOUS EARTH RECOMMENDED TO PRESERVE PUTRESCENT MA- 

 NURES, AND TO PROMOTE CLEANLINESS AND HEALTH. 



The operation of calcareous earth in enriching barren soils has been 

 traced, in a former part of this essay, to the chemical power possessed by 

 that earth of combining with putrescent matters, or with the products of 

 their fermentation — and in that manner preserving them from waste, for 

 the use of the soil, and for the food of growing plants. That power was 

 exemplified by the details of an experiment, (page 60,) in which the carcass 

 of an animal was so acted on, and its enriching properties secured. That 

 trial of the putrefaction of animal matter in contact with calcareous earth, 

 was commenced with a view to results very different from those which 

 were obtained. Darwin says that nitrous add is produced in the process 

 of fermentation, and he supposes the nitrate of lime to be very serviceable 

 to vegetation.* As the nitrous acid is a gas, it must pass off into the air, 

 under ordinary circumstances, as fast as it is formed, and be entirely lost. 

 But as it is strongly attracted by lime, it was supposed that a cover of 

 calcareous earth would arrest it, and form a new combination, which, if 

 not precisely nitrate of lime, would at least be composed of the same ele- 

 ments, though in different proportions. To ascertain whether any such 

 combination had taken place, when the manure was used, a handful of the 

 marl was taken, which had been in immediate contact with the cai'cass, 

 and thrown into a glass of hot water. After remaining half an hour, the 

 fluid was poured off, filtered, and evaporated, and left a considerable pro- 

 portion of a white soluble salt, (supposed eight or ten grains.) I could not 

 ascertain its kind— but it was not deliquescent, and therefore could not have 

 been the nitrate of lime. The spot on which the carcass lay was so strong- 

 ly impregnated by this salt, that it remained bare of vegetation for several 

 years, and until the field was ploughed up for cultivation. 



But whatever were the products of fermentation saved by this experi- 

 ment, the absence of all offensive effluvia throughout the process sufficient- 

 ly proved that little or nothing was lost, as every atom must be, when 

 flesh putrefies in the open air ; and I presume that a cover of equal thick- 

 ness of clay, or sand, or any mixture of both, without calcareous earth, 



* Darwin's Phytologia, pp. 210 and 224. Dublin edition. 



