378 



REIBLING AND REYES. 



coarse particles of lime which have -been calcined at a high enough 

 temperature to cause at least the sintering of their surfaces. 



So much for the appearance and methods of producing the crystals 

 of calcium hydroxide-phenol as they are formed with lime only. Those 

 secured by treating Portland cement are similar to the crystals formed 

 either from pure calcium oxide or hydroxide. 



Underbnrned, nonseasoned commercial cement clinkers, pulverized and with or 

 without the addition of plaster, develop crystals with the test, solution which 

 are identical in appearance with those which we have obtained from calcium 

 oxide. Figures 5 and G are photomicrographs obtained respectively, from pure 

 calcium oxide and from nonsintered lime from Portland cement and figures 

 7 and 8 from lime heated in the electric arc and sintered lime in cement. A 

 comparison will make the fact clear. 



Fig. 5. — Characteristic crystals obtained by 

 the microscopic test from cal- 

 cium oxide ignited at a red heat. 



Fig. 6. — Characteristic crystals obtained by 

 the microscopic test from non- 

 sintered lime in Portland cement. 



Fig. 7. — Characteristic plume-like forma- 

 tions of crystals obtained from 

 sintered lime. 



Fig. 8. — Characteristic plume-like forma- 

 tions of crystals obtained from 

 sintered lime in Portland cement. 



