58 On the Minerals of Canada. 



then acquires the power of absorbing water in the proportion of 9 

 pounds of water to 28 pounds of lime, with the evolution of much 

 heat. If this lime is mixed with sand to the extent of two or three 

 times the weight of the lime, and water added, a mortar is formed 

 which possesses the property of hardening in dry air or between 

 dry bricks, imperfectly hardening in damp air, and refusing alto- 

 gether to become consolidated under the surface of water.' 



2. Water Limes or Hydraulic Limes, or Cement, are those 

 which possess the property, after they have been properly burned, 

 of hardening under water without admixture with any other sub- 

 stance. 



The simplest form of an hydraulic lime, is common lime mixed 

 with 10, 15 or 20 per cent, of clay, or clay and magnesia, or a 

 little clay, sand and magnesia. With such a compound, when 

 calcination or burning is not carried too far, a good and durable 

 cement is obtained, setting under water in periods varying from a 

 few hours to a week or mor6, and at the end of some months be- 

 coming harder than many common limestones. 



Many calcareous clays or argillaceous limestones exist in nature 

 possessing these properties, these are called hydraulic limestones, 

 because when they are partially burned they possess the property 

 of setting underwater. Many limestones v^liich are usedfor hydraulic 

 purposes, possess the very detrimental quality of containing portions 

 of lime after they are burned, which slake at a period subsequent 

 to their use. The mortar or cement then falls to pieces and be- 

 comes not only useless, but absolutely injurious. 



Limestone, containing the proper admixture of the materials 

 enumerated, exists in many parts of Canada; at Paris, Cayuga, 

 Thorold, Kingston, Loughboro', Hull, Quebec and elsewhere. In 

 some of these localities the beds have been worked ; those of Hull 

 are of excellent quality and highly esteemed. This bed is charac- 

 terized by the proximity of a layer filled with a particular shell, 

 and has been traced chiefly by means of this shell over a large area, 

 and it is the continuation of the same bed which furnishes the 

 hydraulic lime of Kingston and Loughboro'. 



In the United States the preparation of hydraulic cement of 

 different qualities, is already a manufacture of considerable import- 

 ance. 



So far back as 1840, there were 60 kilns for the manufacture 

 of cement, in the vicinity of Kingston, Rosendale, Lawrenceville, 

 and High Falls, in the State of New York. In that year it was 



