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its weight of water, forming tbe liquid called lime-water. From its 

 caustic qualities, and its solubility in water, is now generally consi- 

 dered as an alkaline substance. 



From the combination of lime with carbonic acid ; the acid which 

 is formed by the union of carbon, the chief matter of charcoal and 

 of the diamond, with oxygen or the acidifying principle, proceeds 

 carbonate of lime. From this substance, according to its dfferent de- 

 grees of purity, and modes of combination, is formed chalk; a sub- 

 stance which requires no description Tufa, a light porous calca- 

 reous substance, chiefly deposited from water, in which it had been 

 diffused Lime-stones, of various colours and texture, employed for 

 paving, and for various purposes of architecture Marbles, which 

 are finer kinds of lime-stones, possessing a closer texture, and being 

 capable of assuming a good polish Calcareous spar, named accord- 

 ing to the form of its crystals, lenticular spar, dog-tooth spar, &c. 

 Alabaster, formed by the deposition of calcareous matter in clefts of 

 rocks, from the water in which it was suspended Stalactites, formed 

 on the roofs of subterranean cavities by the gradual accretion of si- 

 milar matter, from water filtrating through the more porous lime- 

 stone; and Stalagmites, formed by the deposition of the same mat- 

 ters on the floors of caverns. 



By the mixture of lime with clay, are formed the various marls ; 

 existing, sometimes, in & soft and pulverescent state, and at other 

 times, possessing the hardness of stones. 



By the union of sulphuric acid with lime, is formed gypsum, or 

 selenite, a substance generally of a white colour, and exhibiting a 

 slight degree of lustre and transparency. By intense heat, the lime 

 is obtained from this substance, in a state of considerable purity ; 

 and is then termed plaster of Paris. When combined with the acid, 

 termed fluoric acid, the substance called^wor spar is formed ; which 

 is so well known to you, by the more common name of Derbyshire 

 spar. 



