XXVIII. Analysis of one hundred parts of a dark Bituminous Lime- 

 stone, from the Parish of Whit ef or d in Flintshire, North Wales. 



By EDWARD DANIEL CLARKE, ll.d. 



PROFESSOR OF MINERALOGY IN THE UNIVERSITY OF CAMBRIDGE, 

 MEMBER OF THE ROYAL ACADEMY OF SCIENCES AT BERLIN, 



AND HONORARY MEMBER OF THE GEOLOGICAL SOCIETY. 



[Read 21st June, 1816.] 



X HE .superiority which has been observed in the architecture of 

 the ancient Greeks and Romans, may in some measure be ascribed 

 to the materials used in the construction of their edifices. This 

 remark is especially applicable to the works of the Romans ; be- 

 cause a very principal part of the materials of their architecture 

 consisted of substances that were in their nature artificial. Their 

 aqueducts, walls, and foundations, often consisted of bricks and 

 mortar ; and in the making of mortar, by the judicious use of the 

 pulvis Puteolanu!, a cement was prepared which had the property of 

 becoming indurated under water, in such a remarkable manner, 

 that, in many instances, it acquired a greater degree of hardness 

 than the substances themselves exhibit, which this cement was in- 

 tended to hold together. To this property^ are owing the speci- 

 mens of polished mortar, which exist in the cabinets of antiquaries, 

 derived from ruins upon the coast of Baia, of Puieoli, and of Naples, 

 and wherever else the pulvis Puteolanus was used in the fabrication 

 of mortar, which has subsequently been exposed to the action of 



