The Birmingham age-herald., 1904-04-29
From the New York Sun.

nA0ss.. said 1,trs sns T, mechanical ona at sns,-
 ) nance in making Portland cement than you could expect. Of course. I'm right here in the mill all the time; but I've had an exciting winter for all that.
 We've had several floods and fire in the shops. I've had to do Washingtons s stunt of crossing the Delaware through the ice a number of times. Then I've had one of two bad mixups in the ma- chinery, and a row with the Hunks our Hungarian laborers. Oh, yes; you don't have to get into the Jap war to find excitement.
 "There are mighty few people who un- derstand just what Portland cement is and know how many it uses are. Every body knows that it is used for walks. and the foundations of buildings, but there are many other uses.
 Tn the first place, enormous quantities of cement are used by railroads, for bridge piers and culverts. The railroads have also begun to use 1t for ties; fence posts have been made of 1t, too.
 Walls in Notifications have been built of the cement, and it is made up in the form of building blocks-hollow, and therefore very light, yet as strong as the old-tme solid block of stone. The most curious use of it, though, Is In shps-as a lining to the steel shell of the hull.
 Now, I'll just tell you what the ce- ment is and show you how 1t Is prepared. The foundation is limestone, with cer- tain proportion-of course, each firm has its own formula. which Is trade secret, of magnesia and silicates. There are great beds of limestone in this region. We have our own quarry right at hand, which supplies all we can use.
 "The rocks, as 1t comes from the quar- ry, Is first crushed In a large roller. which reduces it to the size of the lower dressing in a macadam road Leaving this first roller, 1t is carried on by a chain of buckets to another. where 1t goes through the process known as ball. ing
 "In this roller there are placed a num- Der of iron balls. each weighing twenty pounds and about tons weight of them to the crusher. By this process the stone is ground to about the size of gran ulated sugar. The other materials are then added to the crushed limestone.
 "The next step is the baking which is done in long rotary lSilns. As soon as the burning reaches the proper stage, the cllnkers, of a dark green color, are car ried on by the bucket chain to the tube roller, where the final grinding produces a fine powder. In this last stage the heavy balls used in the second roller are replaced by pebbles. which have to be frequently renewed.
 During the process of manufacture 1t is repeatedly tested. The final test is the chemical one, to insure the correct com bination of ingredients. Then there are the mechanical tests. for strength and durability. The powder should be suf- ficiently fine to pass through a sieve with 10000 meshes to the square inch; and there are requirements which 1t must meet as to the time taken in setting and for tensile strength--the power to resist various strains to which 1t may be subjected when in actual structural use. The peculiar property of Portland ce- ment that makes it of great value to builders is it's quality of growing contin- ually harder and stronger in use. "The importance of Portland cement