384 



REIBLING AND REYES. 



Fig. 10 (magnification X 180). — Photomicrograph of calcium hydroxide-phenol crystals 

 o£ the unaerated cement recorded in Table IV. It shows the typical plume-like 

 habit of the crystals. Crystalline formations of this character are characteristic 

 of coarse particles of sintered lime which is free from even partial hydration. 





\ S 





Pig. 11 (magnification X 180). — Photomicrograph of the crystals from the same cement 

 after it had been aerated for eighty hours (see Table IV). It shows the rosettes 

 and the long slender needles which are characteristic of the hydroxide. This figure 

 represents the final stage in the process of hydration of the sintered lime, i. e., 

 the total disappearance of plume-like crystals. 



