PART VI. PORTLAND CEMENT. 



CHAPTER XXII. 

 PORTLAND CEMENT: PRELIMINARY STATEMENTS. 



IN the chapters of the present section the raw materials, methods 

 of manufacture, and properties of Portland cement will be taken up 

 and discussed in turn. In order that the statements made in these 

 chapters and particularly in those on raw materials may be clearly 

 understood, it seems advisable to preface the section with a brief 

 explanation regarding the definition, composition, and constitution of 

 Portland cement. This brief explanation is accordingly given in the 

 present chapter, while in Chapters XXIX and XXXVIII the subject of 

 composition and constitution will be discussed in the greater detail 

 warranted by their importance. 



Origin of the name " Portland ". In 1824 Joseph Aspdin took out 

 a patent in England on the manufacture of a cement by calcining a 

 mixture of limestone and clay. To the resulting product he gave the 

 name " Portland", in allusion to a fancied (and in reality very slight) 

 resemblance between the set cement and the famous oolitic limestone 

 so extensively quarried for building purposes at Portland, England, 

 and known to all English architects and engineers as " Portland stone". 



"Portland" cement obtained its name, therefore, because it looked 

 like Portland stone, and not because Portland was the place of its manu- 

 facture. On the contrary, it is not now, and never has been, manu- 

 factured at either Portland, Me., Portland, Ore., or Portland, England. 

 This statement as to the origin of the name may seem unnecessary, 

 but the writer has found many contractors or other users of Portland 

 cement who believed that the only proper Portland must naturally 

 be made at Portland a belief which is fostered by the myriad of post- 

 offices and villages bearing that name which have sprung up in the 

 wake of the American cement industry. 



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