^255 



even 8-lOths, or 80 per cent, of the whole. The next 

 preponderating ingredient is alumina or clay, and after that 

 comes Lime, a constituent of immense importance, and 

 which I have chosen for the subject of the present paper. 

 Lime, that is, pure Lime, is, chemically speaking, a com- 

 pound of a metal called calcium, (which is enumerated 

 amongst the simple or undecomposible substances,) and 

 oxygen, (another of the simples or elements,) or in other 

 words, it is an oxide of calcium — being composed of twenty 

 parts of the metal to eight parts of oxygen. It has alkaline 

 properties, and is capable of forming neutral Salts when 

 combined with acids. It is slightly soluble in water, one 

 pound requiring for solution seven hundred times its own 

 weight of water. It has a great affinity for carbonic acid, 

 and cannot be left for any length of time exposed to the 

 atmosphere without thence imbibing that acid, by which its 

 weight is nearly doubled, as they combine in the proportion 

 of 55 of Lime to 45 of carbonic acid. It is then called Car- 

 bonate of Lime, and it is in this state that it is generally met 

 with in nature. It is never, I believe, found in its caustic 

 state, or in the form of Quick Lime, except sometimes in 

 the craters of volcanoes, where the heat has dispelled the 

 carbonic acid. The other forms in which it has been 

 discovered to any extent are, as combined with sulphuric 

 acid, forming Sulphate of Lime or Gypsum, and in some 

 districts in conjunction with phosphoric acid, in the state of 

 phosphate of Lime, which is the chief fertilizing ingredient 

 of bones : but my observations will, on this occasion, be 

 confined to its uncombined form as Quick Lime, and as a 

 carbonate. 



No doubt, all who are now present are aware that in 

 order to convert Limestone, or in other words the carbonate, 

 into Quick Lime, it is subjected to a red heat in a kiln for 

 some days; by which the carbonic acid is driven off, and 



