CKMENTS. 'J'iVi 



CHAPTER XVI. 

 Cements. 



THE foQudatioii of tlie manufacture of cements in Russia dates from tlie fifties 

 of the present century, an epoch which is in general memorable in many re- 

 spects, in the history of the making of cements throughout Europe. The position 

 of affairs with respect to the manufacture of cements in the first quarter of tbis 

 century is partially explained by the fact that tlie Roman methods of preparing ce- 

 ments, especially those designed for submarine works, had been lo^t and new ones 

 had to be discovered. 



Although at the very beginning of this century a special kind of local native 

 material was found in England, and immediately after in France, which, after roast- 

 ing, gave a cement of higher and more durable quality than hitherto made (J. Parker, 

 nodules of clay; Lesage, galets de Boulogne); these cements were named sRomart 

 cefnentS) after the ancient makers. However, the development and general extension 

 of the cement manufacture was barred by those elementary conditions to which it is- 

 in principle subject from its chemical aspect. It belongs to the number of those,, 

 perhaps few technical branches, whose foundation as an industrial manufacture cannot 

 be accomplished by a method of initiation or transplantation from one soil to another 

 by the customary empiricals of industry, notwithstanding that the actual technical 

 processes and instruments of the manufacture are as simple as can be, consisting as 

 they do of breaking up the material, roasting it in ovens of well known types, and 

 then pulverizing it in mills. 



Owing to the great variety of the lime stone rocks which can be used in this- 

 manufacture, it must at the very commencement be founded upon a clear knowledge 

 of the elementary principles of chemistry, upon which a choice of the most suitable ma- 

 terial and methods of manufacture are based. In the mean while chemical science,, 

 in which the question of the conditions and processes of the formation of the hydrated 

 silicates, whicli harden under water, was always one of the most complex, notwith- 

 standing its seeming simplicity, only gave its fundamental indications in comparatively 

 recent times. 



