XI, A, 6 



Witt: The Effect of Sulphide on Cement 



211 



After analysis, a quantity of this salt was dissolved in water 

 to make a strong stock solution. The exact concentration of 

 this solution was determined by analysis, and other solutions 

 were made by dilution. The strength of each solution is given 

 in terms of grams sulphur as sulphide per liter. 



A cement which develops faults only after a considerable time 

 has elapsed is worse than one which gives trouble in mixing. 

 A cement which is quick-setting, or which is unsound in the 

 boiling test, is, of course, rejected at once, while one which 

 is satisfactory in the preliminary tests, but ultimately develops 

 objectionable features, is not only valueless but dangerous, in 

 that it may cause failure of the concrete in place. 



Some former work " had shown that cement is very sensitive 

 to the influence of sodium sulphide. With some of the solutions 

 of higher cencentration employed at that time, a number of 

 cements set so rapidly that briquettes could not be molded. 

 Therefore in this work setting time tests were made first. The 

 results are given in Table III. 



Table III. — Effect of various concentrations of sodium sulphide on the 

 setting time of cements." 



Sodium suphide 

 added. 



Initial set. 



Final set. 



Sulpur 

 (as sul- 

 phide) 



per 

 liter of 

 solu- 

 tion, b 



Sul- 

 phur 

 (as sul- 

 hide) 

 per 

 gram of 

 cement. 



A. 



B. 



C. 



D. 



E. 



A. 



B. 



C. 



D. 



E. 



Grama. 



Per 

 cent. 



H. 



m. 



H. 



m. 



H. m. 



H. 



m. 



H. 



m. 



H. 



m. 



H. 



in. 



H. 



m. 



H. 



m. 



H. m. 



0.00 



0.00 



5 



15 



3 



55 



4 32 



4 



26 



4 



14 



9 



6 



6 



40 



7 



16 



7 



4 



6 36 



0.02 



0.0004 



6 



50 



6 



2 



6 25 



5 



32 



4 



22 



17 



10 



13 



55 



13 



55 



14 



29 



9 55 



0.11 



0.0022 



9 



31 



5 



41 



6 24 



5 



31 



4 



30 



22 



37 



14 



8 



16 



47 



14 



9 



11 50 



0.21 



0.0046 



6 



56 



5 



59 



7 11 



6 



39 



4 



33 



14 



39 



12 



4 



12 



7 



12 



24 



8 53 



0.43 



0.0095 



5 



21 



5 



39 



6 6 



5 



46 



2 



55 



12 



6 



11 



39 



11 



45 



12 



9 



9 8 



1.06 



0. 0233 



6 



54 



5 



2 



5 37 



4 



54 



2 



51 



12 



32 



11 



17 



11 



20 



11 



39 



8 11 



2.13 



0. 0469 



5 



58 



5 



5 



5 26 



4 



5 



2 



1 



15 



6 



11 



42 



7 



16 



6 



50 



6 16 



2.96 



0.0651 



5 



38 



5 



46 



5 8 



3 



35 



1 



1 



14 



16 



9 



11 



6 



58 



6 



35 



5 21 



5.93 



0. 1305 



4 



13 



4 



40 



4 07 



1 



16 







44 



7 



26 



8 



35 



6 



27 



6 



34 



4 46 



10.00 



0.2200 



1 



42 



4 



44 



4 44 



1 



3 







35 



5 



38 



7 



49 



7 



49 



3 



1 



3 5 



20.00 



0. 4400 



1 



19 



2 



57 



2 57 







58 







29 



4 



48 



6 



12 



6 



42 



3 



37 



2 59 



» Soundness tests were made, and each was found to be satisfactory. 



» The concentrations of the solutions are given in terms of sulphur (as sulphide) per liter. 

 The sulphate was determined, but was negligible. 



" Unpublished results obtained by Witt, J. C, and Baptie, J. A. 



