534 CEMENTS, LIMES, AND PLASTERS. 



Plant No. 14. Dry process: 10 kilns, about 1600 bbls. per day. 

 7 ball mills; 

 7 tube mills. 



Plant No. 15. Dry process : 8 kilns, about 1300 bbls. per day. 

 4 ball mills; 

 6 tube mills. 



Plant No. 16. Dry process : 6 kilns, about 1000 bbls. per day. 

 4 ball mills; 

 4 tube mills. 



Plant No. 17. Dry process: 6 kilns, about 1200 bbls. per day. 

 1 kominuter and 3 ball mills; 



4 tube mills. 



Plant No. 18. Wet process: 21 kilns, about 3000 bbls. per day. 



32 Griffin mills. 

 Plant No. 19. Dry process : 10 kilns, about 1700 bbls. per day. 



5 rotary coolers; 



5 ball mills; 



6 tube mills. 



Plant No. 20. Wet process: 10 kilns, about 1400 bbls. per day. 



1 cracker; 



2 kominuters; 

 5 tube mills. 



Plant No. 21. Dry process : 3 kilns, about 450 bbls. per day. 



1 Williams mill; 



2 tube mills. 



Plant No. 22. Dry process : 4 kilns, about 700 bbls. per day. 



1 cracker; 



7 Griffin mills. 



Plant No. 23. Dry process: 2 kilns, about 300 bbls. per day. 



2 ball mills; 

 2 tube mills. 



Use and Effects of Gypsum or Plaster. 



The high-limed clinker now produced in the rotary process is nat- 

 urally very quick-setting. In order to retard its set sufficiently to pass 

 commercial requirements, sulphate of lime, in the form of gypsum or 

 plaster, is now universally employed. This substance, when added 

 in quantities up to 2 to 3 per cent, retards the set of the cement pro- 

 portionately, and also increases somewhat its tensile strength in short 



