078 KKW TOKK STATE VIH.CM 



hydraulic lime must be carried on voiy -lowly. 



igher the percentage of total Bilicates, the lower must l>o 



temperal burning, for under no circumstances Bhould 



the material be allowed to sinter as it does in the case of Portland 



een 5 i rburned pieces slake very Blowly. Further- 



. the burning Bhould on to the point of driving off the 



The 1 est hydraulic lime known is the celebrated Chaux Ju 



Teil wl mposition according to Dr Michaelis is: 



ica 22.588 



Alumina 2.629 



Iron oxid . 837 



Lime 65.624 



Magnesia 1 . i 



Potash 124 



- da 005 



Sulfuric acid 523 



Ignition G . 424 



Hydraulic limes have generally a yellow color. Their specific 



ity Ls about 2.9 and on ignition they lose about 8#. They 



harden slowly and their hardness by themselves is small. On 



the other hand if mixed with sand they develop a high degree of 



ile strength. 



Natural or Rosendale cements 



Under this heading are included those made from lime-tones 



which have over 2fW of aluminous impurities, and which, when 



and finely ground, harden with water in a short time. This 



includi Roman cements used abroad, and also the dolomitic 



cements made from magnesian limestones. They do not develop 



much heat on mixing with water, and their strength does not equal 



the artificial or Portland cement They differ from hydraulic 



limes in their quicker Bet, and lower percentage of lime. The 



following anaylses given by U. Cummings 1 indicate the wide 



range of materials included under this class. Some authors in 



groups of the dolomitic and Roman cement ma- 



• Ami i lean oements, p, 



