The Birmingham age-herald., 1923-02-18
TWO NEW PLANTS. DRAW ATTENTION
 CEMENT's STRIDES.
First Kiln in America Began Operations in 1872-Ala- bama Plants Swell Pro-
 duction Enormously

Rapid strides of the cement indus try. which Is finding present express sion in Birmingham by the stimuli taneous building of 1000. 900 -barrel Portland cement mills by two of the largest producers in the country, the Raleigh and Phoenix Portland Ce ment companies, has directed atten ton to the history of that industry fin this country and to the remarkable improvement In methods of manufac- ture that have been instituted since the first mill was placed In operation at Coplay. Pa, in 1872.
 The old brick cement ki1ns have been replaced by rotary steel kilns producing many times the product of the original ones and causing total production that was undreamed of as a possibility in the pioneer cement days.
 The Atlas Portland Cement com pany's mill at Leeds, near Birming- ham, and the two new ones being built in Birmingham are the last word in cement mill construction and khe three of them will produce more cement than is at present produced fin the entire state.
 Photographic reproductions in an other column show the original and present style of cement kiln. An in teresting sketch of the history or cement from the time of the Romans until today by Kenneth Rotharmel, of Chicago, is given below. MT. Roth armel is a brother of Mrs. Ralph R. Silver of Birmingham. and was for merly a reporter on The Age-Herald.
 Roman Correct.
 When the builders of ancient Rome designed and constructed the dome of the Pantheon, it was to the vol canoes that they turned to secure a building material that would suit their purposes The terrifying erup- tions that carried death and destruc- tion in their wake had beneficial quality that the Romans were aware of They had discovered the secret of mixing slaked lime with the vol canic ash and producing natural cement. It was material of this kind that entered into so many of the old Roman works. which arc still stand ing. This secret was also known 10 the ancient Carthagenians. who con structed Ia 70-mile aoueduct in north -ern Africa long before the holy Roman empire was even thought Of.
 Secret Lost for Ages
 whether the ancients realized just what the seething volcano did to raw materials to give them their cement ing qualities is a matter of conjec- ture. It is known, however. that the secret was lost for centuries during the dark ages, and that 1t was not until 1756 that the threads of the art were picked up again. In that year an English engineer named John Smeaton was awarded a contract to construct lighthouse in the English channel. Several structures had al- ready been built and destroyed on this site. SIneaton's main problem was to find a material that would harden under water. and withstand the fury of the channel gales. The contract became an obsession. with him. and he determined to erect a monument to his engineering skill.
 Lost Art Revived
 Throughout the long winter months Smeaton experimented with various materials, finally discovering that an impure limestone containing certain amount of clayey matter possessed decided cementing qualities when it was burned. His material would harden under water, and his problem was solved. The lighthouse was constructed of his newly discov- cred product and stood for many years before it was torn down to erect a larger one.
 In 1924 Joseph Aspdin, another Englishman. took out patent for portland cement, naming it port land" because when 1t hardened it re- sembled a grayish stone found on the Isle of Portland, off the coast of Eng land. The features of Aspdin's pat ent were that he mixed limestone or its equivalent, chalk, with shale or clay; he burned the mixture, then he ground it. His material differed from that of Smeaton because he recog- nized the value of proper proportions of the various materials and the ne- cessity of burning at high tempera- ture.
 Artificial VoIcanos
 To carry out the burning process, which had been done for the Ro- mans by the volcanoes. it was neces- sary to construct kilns, which resem- bled huge beehives. They were. in sense, artificial volcanoes, in which the secret of the old Romans was re- produced.
 The art of making portland cement did not reach the United States until 1872, when kilns were constructed at Coplay Pa. Natural cement had been made here six years prior to that time. Within a few years plants were operating in various parts of the country. In the vicinity of Coplay many of the old ruins of the first kilns are still standing. They served their purpose for short time, but were soon abandoned for more mod ern methods of manufacture, as car ried out by the rotary kilns of today.
 The difference between the old nat ural cements of the Romans and the portland cement of today Is that the