CALCAREOUS MANURES— APPENDIX. 287 



which is still deemed the best for separating the particles of lime and spread- 

 ing it equally over the land ; and also (I will add, as another important 

 object,) to permit the quick-lime by exposure to become again combined 

 with carbonic acid in the shortest time. 



" Close kilns, with walls of brick or stone, have not yet been used to burn 

 oyster shells for manure ; and until fuel becomes more costly than the ad- 

 ditional transportation of the lime, it will be cheaper to use wooden kilns. 

 What are commonly called lime kilns are merely heaps of wood and shells, 

 built up in a somewhat cubical form, by which the burning is imperfectly 

 performed at great expense of fuel though without much trouble. Mr. Lewis 

 burns his shells in the following manner. A pen of sixteen or seventeen 

 feet square, is built of round green pine logs, (notched where they lock, 

 so as to come as close together as their form will allow,) and with a floor of 

 similar logs, chinked with smaller pieces, so as to prevent the shells drop- 

 ping through. The bottom logs of the kiln are laid on four corner blocks, of 

 twelve inches, so as to leave a vacancy of twelve or fifteen inches between 

 the earth and the bottom of the floor, which is to be packed closely with dry 

 wood. The walls of the pen are raised about nine feet ; and about one 

 hundred logs of six to eight inches through (which these now put up seemed 

 to be,) usually serve for the floor and side walls. The shells are thrown in, 

 and in layers of different degrees of thickness, according to their order, and 

 separated by thin layers of pine wood, cut eight feet long, and split to the 

 usual size for fuel. The size of the last kiln burnt by Mr. L., according to 

 his memorandum book, was as follows: 



Kiln 17 feet square and 9 feet high, inside measure. 



The lowest bed of shells 8 inches (he thinks it might as well have been 

 12 inches.) 



The second bed of shells 12 inches, 

 third 16 



fourth 20 



fifth 15 



sixth 6 



The layers of wood between were equal, and about six inches. The kiln 

 took one hundred hogsheads of shells, and consumed ten cords of wood in 

 the layers, and three more of foundation or kindling wood. The kiln should 

 be fired in calm weather ; and if the wind afterwards rises, it should be 

 kept off" as much as possible by a screen of brush, or whatever may be most 

 convenient. 



The burning (in preference) is done in March, or as soon after as may be. 

 The newly burnt shells are carted to the field as soon as they ai'e cold enough, 

 and deposited in small parcels of a measured heaped half bushel each, at 

 distances of six yards. The field is previously ploughed, and marked oflf 

 carefully in checks of six yards square. These small heaps of shells are 

 immediately covered completely, but not heavily, by the surrounding earth 

 being drawn over them with broad hoes. If a heavy rain was to catch the 

 lime before this covering, much of it would become a wet sticky mortar, 

 difficult to manage, and impossible to distribute equally. When secured in 

 the heaps, the moisture absorbed from the earth will usually slake the lime 

 in forty-eight hours. The heaps are then cut down and mixed with hoes, 

 and carefully spread so as to cover the field very equally. The land is then 

 well harrowed, more effectually to distribute and mix the lime with the soil. 

 The quantity applied to the acre is about seventy bushels of the burnt and 

 unslaked shells, which quantity is produced by burning 6 hogsheads (108 

 bushels) of shells ; and the same, if well burnt, will swell in slacking to 125 

 or 130 bushels. The lime is always put on a part of the field of the fourth 



