2 The Philippine Journal of Science i9i8 



termination of acidity and a rough estimate of the total amount 

 of solid matter have been added, the soap method for total 

 hardness has been replaced by a new and more accurate proce- 

 dure, and several minor modifications in the details of manipula- 

 tion of some of the old methods have been introduced. Other 

 minor changes have been made in apparatus, as will become 

 evident in the detailed description to follow. 



In connection with the study of potable waters, a field bac- 

 teriological examination is also made. This consists in 24- and 

 48-hour colony counts at ordinary temperature and a presump- 

 tive test for Bacillus coli or related organisms that would indicate 

 faecal contamination. The uniform tropical temperature (25° 

 to 30° C.) makes this bacteriological work a very simple, while 

 a very valuable, feature of the examination. 



The outfit has been gradually reduced in size, although the 

 number of determinations made has been increased; so now 

 enough apparatus and materials for a month's chemical work 

 can be carried in an army telescope. This makes a package 

 weighing less than 20 kilograms, which fits well on one side 

 of a packsaddle or on the back of a cargador. The bacterio- 

 logical outfit is carried in a small metal box. The complete 

 equipment is shown in Plate I. 



A comprehensive sanitary survey, embracing, in so far as 

 possible, all those features that might influence the quality of 

 the water under examination, is, of course, included in field work. 



The details of the methods employed in regular field examina- 

 tion are outlined and briefly discussed. 



Table I. — Chemical methods. 



Quantitative. Qualitative. 



Color Odor 



Turbidity (as SiOs) Total solids 



Alkalinity (as CaCOa) Appearance on ignition 



Acidity (as CO'') Calcium 



Iron (Fe) Classification for boiler use 



Chlorides (CI) 



Normal carbonates (as NajCOa) 

 Bicarbonates (as CaCOs or 



HCOs) [by calculation] 

 Sulphates (as SOa) 



Total hardness (as CaCOa) : 



Estimated encrustants 



[by calculation] 



Color is determined with the United States Geological Sur- 

 vey color outfit described by Leighton,^ consisting of a standard 



•Op. cit. 



