282 



The Philippine Journal of Science 



1916 



relative loss is not so great as with the five cements previously- 

 tested. Apparently the added iron oxide in sample G has little 

 effect as far as the sulphide is concerned, but causes a lowering 

 of the tensile strength as any foreign substance is likely to do. 

 The fact that the added iron is not so finely divided nor so 

 uniformly distributed as that originally present no doubt partly 

 accounts for the difference in behavior. 



PERCENTAGE LOSS IN TENSILE STRENGTH 



It is evident that in comparing the loss in tensile strength with 

 the iron content of the cements and with concentrations of the 

 sulphide solutions, the percentage loss should be the true basis 

 of comparison. Accordingly Tables VII and VIII have been pre- 

 pared. Table VII shows the percentage loss in tensile strength 

 for the cements of various iron content when gauged with the sul- 

 phide solution having the highest concentration (No.l). Table 

 VIII shows the percentage loss in tensile strength of brand A 

 when gauged with sulphide solutions of various concentrations. 

 This brand has the highest iron content of any of the cements 

 studied in detail. The values given in these two tables may be 

 taken in general as typical of the tensile strength results, al- 

 though some of them are not so regular. This can be understood 

 by remembering that a great many factors other than the iron 

 content and sulphide concentration influence the strength of these 

 briquettes. In general, the relation between percentage loss in 

 tensile strength and iron content is not so well established with 

 the mortar briquettes as with the neat briquettes. 



Table VII. — An example of variation of percentage loss in tensile strength 



with the iron content. 



Brand. 



Iron 



oxide 



(Fe203). 



Tensile strength in 



kilos per square 



centimeter.* 



Tensile strength in 



pounds per square 



inch. 



Loss in 

 tensile 

 strength 

 in kilos 

 per sq. 

 cm. 



Percent- 

 age loss. 



With 

 water. 



With 

 solution 

 No. 1. 



With 

 water. 



With 

 solution 

 No. 1. 



D 



Per cent. 

 1.12 

 1.34 

 1.38 

 1.42 

 3.44 

 8.63 



50.6 

 45.7 

 51.3 

 48.1 

 48.1 

 38.7 



41.2 

 34.7 

 37.9 

 27.4 

 23.9 

 20.4 



722 

 651 

 731 

 685 

 685 

 550 



584 

 495 

 539 

 391 

 341 

 291 



9.4 

 11.0 

 13.4 

 20.7 

 24.2 

 18.3 



18.58 

 24.07 

 26.12 

 42.62 

 -50. 31 

 47.29 



B 



E 



A 



F 



G 





' All briquettes were made of neat cement and broken at the end of seven days. Brand 

 C shows irregular results, and since it has the same iron content as brand D, the results have 

 been omitted here. 



