672 Transactions of the American Institute. 



cular arrangement and disposition of the particles of the rarefied gas 

 necessary for the propagation of electricity. 

 Dr. A. Ott then read the following paper : 



Hydraulic Cements — Their Adaptability for Useful and Orna- 

 mental Purposes. 



PART 1. 



There are few branches of industry which to-day present more 

 practical interest than that pertaining to the application of hydraulic 

 cements. They are not only of the greatest importance for all con- 

 structions under water, but they are also capable of replacing the 

 natural stone for superstructions in most, not to say in all, instances. 

 Unless the use of mortar be abstained from altogether, and large and 

 carefully prepared building stone used instead, it would be impossible 

 to erect a building under water without having recourse to hydraulic 

 cement. The enormous expense and the difficulties of the latter 

 method would undoubtedly reduce the number of such constructions 

 to a minimum. " Where, for instance, we now see imposing light- 

 houses boldly defying the threatening pressure of the waves, the 

 mariner might be exposed to all the dangers of the coast without a 

 warning signal or a guiding beacon. Where splendid ports, with 

 massive docks and bulwarks, most effectually protect trade and com- 

 merce against the indomitable action of a powerful element, we should 

 probably find no trace of the lively intercourse and international com- 

 merce which animate our principal seaports, had not chemistry given 

 us means to replace, by art, what nature has either refused or granted 

 only at a few exceptional places. 



" For the security of commerce, for coast defense and protection, 

 for the intercourse on our water roads in the interior, and for a thou- 

 sand other purposes, hydraulic cements are of the highest importance. 

 1 Concerning their use for buildings above water,' says Michaelis, ' it 

 may safely be asserted that they have made a remarkable impression 

 on our modern architecture, and have replaced the old stiff and 

 clumsy masses by elegance and boldness of conception. One need 

 but compare the columns, arches and lofty balconies of European 

 capitals with those of former periods, to see how much more ease and 

 freedom characterize our modern style. It seems as if the architect 

 knew how to influence his design by his genius ; yes, as if he had 

 succeeded in freeing himself, as if by magic, from the fetters of gravi- 

 tation to which all matter is inevitably subjected.' ' : 



