GRANITE. — LIME. 



347 



ing to the place and manned by her own citizens ; 

 and of these vessels Dr. Jackson states that more 

 than 100 are constantly employed. The measure 

 of a lime-cask is fixed by law at 40 gallons, and 

 they hold 300 lbs. of lime. A kiln capable of burn- 

 ing 300 casks of Hme is 14 feet long, 14 feet high, 

 and five feet deep. It has three pointed arches,* 

 that in the centre being five feet high. The kilns in 

 Maine are usually built of talcose slate. 



Lime is burned very extensively on the Hudson 

 River, particularly at Barnegat, where the kilns are 

 kept constantly burning from the opening of the 

 river in the spring until the closing of it in winter, 

 without allowing them to cool. The method pur- 

 sued here is, after the kiln is once kindled, to charge 

 about half a ton of anthracite coal, broken to the 

 egg size ; then 300 to 350 bushels of limestone, in 

 lumps of 20 to 30 pounds each; and at the end of 

 12 hours another charge of coal and limestone, and 

 so on till the kiln is filled. They then draw out 

 about 850 bushels of lime from the bottom, and in- 

 troduce another charge of coal and limestone, and 

 every 12 hours this process is repeated. This oper- 

 ation is continued for months, as in a furnace for 

 smelting iron. A great economy is thus introduced ; 

 the kilns being always kept heated, and the heat 

 which would escape in the common mode of man- 

 ufacture is here expended in heating other portions 

 of limestone, and preparing it for the high tempera- 

 ture necessary to expel the carbonic acid. About 

 700 bushels of lime are thus obtained daily from 

 each kiln, with the consumption of a little less than 



* « There are many improvements," says Dr. Jackson, ** to 

 be made m the method of burning lime, and one of these con- 

 trivances consists in having lateral arches, in which the v^rood or 

 coal IS consumed, while the flame and current of heated air 

 draw through the limestone, and keep it constantly red-hot. It 

 is then, when sufficiently burned, drawn out, and more rock is 

 to be added to the top of the charge." 



