fire-resistive building material of wide application, pro- 
duces a monolithic unit or structure and permits reinforce- 
ment with steel to produce additional strength. 
A little more than half a century ago, nearly all of the 
portland cement used in America was imported. Since 
then, production in this country has increased from 170,000 
sacks in 1890, to about 390 million sacks in 1920. There 
are four sacks to a “barrel.” Comparatively little now is 
imported. 
“PORTLAND” A DEFINING TERM APPLYING TO 
A VARIETY OF BRANDS 
The first use of a material similar to cement for binding 
together fragments of stone cannot be traced as it extends 
beyond ancient-written history. But, as already noted, 
it is known that the Egyptians and Romans prepared a 
mortar which would harden under water. In 1824, Joseph 
Aspdin, a bricklayer of Leeds, England, patented an arti- 
ficial cement which he called “portland” because of its 
resemblance in color to a building stone obtained from the 
Isle of Portland, off the coast of England. In the early 
days, cement was made by a mechanical or physical mixture 
of various materials or by heating a clayey limestone to a 
relatively low temperature. Today, different materials 
first are “mixed” mechanically and then “combined” 
chemically by intense heat. Cement so made, irrespective 
of brand, is known as “portland” cement to distinguish 
it from “natural,” “‘puzzolan” and other cements now little 
used. 
What is now the Universal Portland Cement Co. first 
made a puzzolan cement at the rate of 300 sacks a day. 
In 1900, it began the manufacture of portland cement and 
shipped that year 82,000 sacks. Today, the Pittsburgh 
plant alone has a producing capacity of 44,000 sacks a day 
while the company’s total capacity is 160,000 sacks a day 
or 48 million sacks a year.