002 Transactions of the American Institute. 



and used to some extent as a building material, but the slowness 

 of the induration, and uncertainty in the product, hindered its 

 general introduction. The improvements referred to consist in the 

 use of heat in connection with quicklime and sand, by which the 

 formation of the silicate of lime is hastened, and the same elfect, 

 which formerly took years to be consummated, is now produced in 

 a few days. Ground quicklime is thoroughly mixed with clean, 

 sharp sand, and is then subjected to the action of either super- 

 heated or high pressure steam, which slacks the lime, and causes it 

 to attack the silica. This process continues for from twenty minutes 

 to ten days, according to the degree of heat employed, when the 

 material is molded and compressed by a heavy steam hammer into 

 blocks of any desired form. The ordinary building block made b}^ 

 this process is ten inches wide and four inches deep, having a hol- 

 low space in the center six inches long by one inch broad; when 

 the blocks are placed upon each other, so as to break jointi^, a con- 

 tinuous and connected series of air chambers will be formed within 

 ' the wall. Thirty days exposure of the block, after it is first formed, 

 to the air, produce an induration quite sufficient for all ordinar}' 

 building purposes, but the block continues to harden for an 

 unlimited period. A church built entirely of this material was 

 recently dedicated at Morrisania. A number of tine buildings 

 have already been constructed of this material in Chicago, among 

 w^hich may be mentioned a handsome block of dwellings on Six- 

 teenth street, and the Young Men's Christian Association of the 

 same city, w^hich was recently burned. The endurance of this stone, 

 when submitted to repeated freezing and thawing, is quite remark- 

 able, and experiment proves it to be equal in this respect to granite. 



Richardson's process for making steel. 



Many of the puddling furnaces of Great Britain have lately been 

 improved by the addition of an apparatus for blowing air into 

 them, resembling that used by Bessemer in making steel directly 

 from the ore. The application of the improvement requires no 

 alteration in the form of the common puddling furnace, for it does 

 not essentially change the old method of puddling; but by intro 

 ducing air through the iron rake or rabble used to stir the metal 

 it reduces in quality or duration one particular stage of the process 

 Instead of numerous small holes in the blast-pipe or tubular rabble 

 to subdivide the current of air, there is one broad slit of rectauofu 

 lar opening, about half an inch wide, and three or four inches long 



