TOBK II 



in •ti\«-lv, the larger mill is worl 



the hourly output being " s -40 

 ound to about 50. The Bmaller Bized mill is 



I on tailings from tic ratora and clinker from I 



crusher m . rough grating being placed in the clinker hop- 



Mt any pieces larger than a walnut from g for- 



ward int<» the mill. would choke the worm feed. 



The Bmaller mill under these conditi I to yield l'G-:JU cut 



an hour. 



Mills compared, II. Faija makes the following compi 



The power consumed by the several principles, reduced to the 



proportions of 1 ton of cement an hour, may he approximately 



ted a- follows: for millstones 30-32 horse power per ton an 



hour; hall principle 16 I s : edge runner principle 12-14. In 

 ement i- ground to a fineness of a .". • residue on 

 and it will thus be seen that the power required 

 is proportionate to the amount of flour produced. 



Butler declares, from microscopic analysis of different cements, 

 that the Btatement that millstones produce an angular grain, and 

 _e runners a rounded one, i.- incorrect. 



Testing 

 Tin yet no universally accepted standard methods 



ing, but the characters which may be, and often are deter- 

 mii compressive strength; tensile Btrength; rate of set- 



_: boiling test; abrasion; permanency of volume; degree of 



gravity. 



Mixing flif mortar 

 In ' erican society of civil engineers ^mr^o-fed I 



of oeat cement, and. in addition, briquets of cement 

 nd: those "i" natural cement with one part Band, and th 

 -Hand cement with three parts Band by weight. Some au- 

 thority ndonment of the mat cement test, since 

 in 086 thi nixed with .-and. The rati" «.f 



