LIME AND CEMENT INDUSTRIES 743 



CLIPS 



For using tlie clips recommended in the preliminary report it 

 was found in some instances that the specimens were broken at 

 one of the points where they were held. This was undoubtedly 

 caused by the insufficient surface of the clip, which, forming a 

 blunt point, forced out the material. Where the specimens were 

 sufficiently soft to allow this point to be embedded, they broke 

 at the smallest section, but, when hard enough to resist such 

 embedding, they showed a wedge-shaped fracture at the clips. 

 To remedy this, the point should be slightly flattened, so as to 

 allow of more metal surface in contact with the briquet. Clips 

 made in this way have been used, and good results obtained. 



To adapt the one inch clips of the Riehle machine, only a slight 

 amount of work is necessary; the ends being rounded, will admit 

 the proposed new form of briquet, and yet not prevent the use 

 of the old one, thus allowing comparative tests of the two forms 

 to be made mthout changing the clips. 



There should be a strengthening rib upon the outside of the 

 clips to prevent them from bending or breaking when the speci- 

 mens are very strong. 



The clips should be hung on pivots so as to avoid as much as 

 possible cross strain upon the briquets. 



MACHINES 



'No special machine has been recommended, as those in common 

 use are of good form for accurate work, if properly used, though 

 in some cases, they are needlessly strong and expensive. Machines 

 mth spring balances are to be avoided as more liable to error 

 than others. 



It is by no means certain that there exists any great difference 

 in well made machines of the standard forms given. 



AMOUNT OF MATERIAL 



The amount of material needed for making five briquets of 

 the standard size recommended is : for the neat cements, about 

 one and two thirds pounds; and for those with sand, in the pro- 

 portion of three parts of sand to one of cement, about one and 

 one quarter pounds of sand and six and two thirds ounces of 

 cement. 



German specifications for standard Portland cement tests 



Definition. Portland is a product resulting from the vitrifica- 

 tion of a thorough mixture of material, whose principal component 



