xiii. A, 1 Behrman: Determination of Hardness of Water 



27 



Table II. — Comparison of field and gravimetric determinations of total 



hardness." 



No. 



Calcium. 



Magne- 

 sium. 



Total 

 hardness 

 (calcu- 

 lated). 



Total 

 hardness 



(field 

 method). 



Error 

 (per 

 cent) . 



1 



140 

 36 

 94 

 80 

 34 

 12 

 92 

 81 

 40 

 54 

 36 

 38 



11 

 14 

 21 

 24 

 25 

 3.8 

 28 

 23 

 15 

 37 

 16 

 12 



395 

 150 

 320 

 300 

 185 

 46 

 345 

 300 

 160 

 290 

 160 

 145 



385 

 165 

 340 

 285 

 195 

 49 

 350 

 290 

 170 

 290 

 165 

 150 



2.5 

 10.0 

 6.3 

 5.0 

 5.4 

 6.5 

 1.5 

 3.3 

 6.3 

 0.0 

 3.1 

 3.4 



2 



3 . 



4 1 



5 _ 



6 



7 



8 



9 - . . 



10 



11 



12 













4.5 













" The gravimetric determinations herein recorded were made by Mr. J. Gonzales y Nufiez, 

 Inorganic chemist. Bureau of Science. 



SUMMARY 



Two methods have been cJescribecJ for the rapid determination 

 in the field of the total hardness of water. Both methods have 

 been shown to be applicable to field investigations, though pre- 

 ference has been given to the second procedure. The latter has 

 been employed, with satisfactory results, for the past eight 

 months in connection with the water survey made by the Bureau 

 of Science. 



