402 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



The process of preparing this concrete, or Beton Coignet, con- 

 sists simply in mixing a- large quantity of sand with a small 

 quantity of hydraulic lime, to which has been added a mi- 

 nute portion of Portland cement. This mixture, slightly 

 moistened with water, is subjected to an energetic trituration, 

 with compression, so as to produce a pasty or pulverulent 

 powder. This pasty powder is then thrown in thin layers 

 into moulds, where it is agglomerated vigorously by the blows 

 of a hammer, causing it to set almost instantaneously. In 

 less than eight days the concrete becomes so hard as to al- 

 low of the removing of the centering from arches twelve feet 

 in diameter, a thing which could not be properly done in the 

 same time with the best masonry. 



This new concrete is now applied in France to a great va- 

 riety of subjects palaces, private residences, churches, arch- 

 ways, reservoirs, sewers, water-pij}es, etc. all capable of be- 

 ing formed out of a single piece ; of the greatest solidity ; of 

 perfectly smooth exterior, and susceptible of embellishment 

 with every variety of adornment ; impervious to water ; se- 

 cure against the action of frost ; and all at an expense very 

 appreciably less than that of ordinary masonry. 



Our space does not permit us to go into further detail on 

 the subject, for which we would refer to the report in ques- 

 tion, but simply to suggest that in this substance, requiring 

 only sand in large quantities for its preparation, we may find 

 the practical solution of the difficulties in engineering in many 

 portions of the Southern States and elsewhere, where natural 

 rock suitable for building purposes is not to be obtained ex- 

 cept by transportation from great distances. 4 J?, 1870, 25. 



SOREL CEMENT. 



According to the Quarterly Journal of Science, the sorel 

 cement, which has attracted so much attention of late by its 

 permanence and close imitation of various natural tones, is 

 made by diluting or tempering magnesia, which maybe more 

 or less hydrated and carbonated, with a solution of chloride 

 of magnesium in a dry state, and employing water to form 

 the cement. The cement thus produced is especially white 

 and hard, and may be used with advantage in place of some 

 of the best cements. It possesses the same hardness, and will 

 receive the same polish as marble, mosaic pavements, and 



