PROPERTIES OF PORTLAND CEMENT. 



411 



Fig. 15. — Photograph of sound and disintegrated commercial Portland cement clinkers. 

 (1) Characteristic sound, weathered, stationary kiln clinker split open to 

 show its homogeneous and perfectly sintered condition ; (2) piece of raw-meal 

 brick which had almost escaped the fire ; the particles of ground limestone 

 ■were held together by the cohesion of the dehydrated, compressed clay ; this 

 shows one possible source of the carbon-dioxide in commercial cements; (3) 

 characteristic disintegrated product of weathered, underburned, stationary kiln 

 clinker. 



