"74 S KEW YORK STATE MUSEUM 



mixed dry in a vessel, and 160 ccm of water are added thereto, 

 and then the mortar is thoroughly mixed for five minutes. Of 

 this mortar 850 grams are placed in the cubic molds, provided 

 with guide mold, and the mold is then screwed on the bedplate 

 under the pounding machine. The iron follower is placed in 

 the form, and, by means of Eohme's trip hammer, 150 blows 

 are struck, by a hammer weighing 2 kilograms. 



After removing the guide mold and follower, the test piece is 

 smoothed off, with the mold from the bedplate, and for the rest 

 treated as for hand work, as given above. 



MAKIWa TEST PIECES OF NEAT CEMENT 



The inside of the molds is slightly oiled, and the same are 

 placed on a metal or glass plate without blotting paper. 1000 

 graius of cement are weighed out, 200 grams of water are 

 added, and the whole mass thoroughly mixed for five min- 

 utes (best with pestle). The forms are well filled (rounded), 

 and then proceed as for hand work as given above. The 

 molds can only be taken off after the cement has sufiiciently 

 hardened. Since, by the pounding in of the neat cement, test 

 pieces of uniform consistency are to be obtained, for finely ground 

 or quick setting cements, the amount of water must be corre- 

 spondingly increased. The volume of water is always to be 

 stated in giving the strength obtained. 



TliEATMENT OF TEST PIECES AT TIME OF TESTING 



All specimens are to be tested directly after their removal from 

 the water. Since the time of testing is of influence on the result 

 in tensile tests, the increase of load shall be 100 grams 

 per second. The mean of the four best results shall be consid- 

 ered the final tensile strength. In testing compression pieces, 

 the pressure is always to be exerted on two side faces of the cube, 

 but not on the bottom or top. The mean of the four highest tests 

 -shall be considered as the final compressive strength. 



Abstract from French, specifications for Portland cement 



CIIEMICAE ANALYSIS 



The cement must not contain more than 1^ of sulfuric acids 



or sulfids in determinable proportion. Cements containing more 



than 4^ of ferric oxid, or in which the ratio of the combined silica 



and alumina to the lime is less than .44, are to be regarded as 



doubtful . 



