determioations were made, using a 

 glass disc color comparator when 

 an electrometric unit was judged 

 unreliable (following a trip over 

 rough roads) and as a check on 

 the electrometric measurement. 



c. Dissolved oxygen - samples were 

 dosed at the time of collection 

 with reagents for the sodium 

 azide (Alsterberg) modification 

 of the Winkler method. Percent 

 of saturation was computed using 

 sea level saturation values at 

 the temperature of sample collec- 

 tion. Percent of saturation 

 values were not corrected for the 

 altitude of sample collection, 

 i.e., barometric pressure. 



d. Carbon dioxide - total carbon 

 dioxide was approximated by add- 

 ing 0.02 N NaOH to the phenolph- 

 thalein endpoint in a carefully 

 collected sample. 



e. i\mmonla - sample was preserved 

 with 0.8 ml. of concentrated 

 HoSOi^ per liter of sample at time 

 of collection. 



f . Alkalinity - total bicarbonate a 

 and carbonate (if present) edka- 

 linity were deteimined by titra- 

 tion with 0.02 N HgSOi^ against 

 the phenolphthaleln and methyl 

 orange endpoints. 



g. Hardness - total hardness was 

 measured by titration using the 

 SchwajTzenbach method. Carbonate 

 and noncarbonate hardness were 

 calculated, using the total hard- 

 ness — total alkalinity relation- 

 ship. 



Determinations made on samples 

 brought back to the laboratory and the 

 analytical procedures used were as follows: 



a. Color - "Aqua Tester" was used to 

 measure color by comparison with 

 a glass disc calibrated against 

 platinum-cobalt standards. Exces- 

 sive turbidity was removed by 

 centrifuging when necessary. 



b. Turbidity - A Hellige turbidi- 

 meter was used to measure low 



turbidities. If turbidity valxies 

 exceeded 30* th* sample was di- 

 luted with distilled water. The 

 turbidimeter was calibrated 

 against a Jackson candle turbidi- 

 meter. 



c. Conductivity - specific conduct- 

 ance was measured using a Wheat- 

 stone bridge and a specific 

 conductance cell, calibrated 

 against a standard ¥321 solution. 

 Values were recorded in micrcmho*/ 

 cm. , corrected to 25° C. 



d. Ammonia - determinations were 

 made by direct nesslerizatlon In 

 nessler tubes, and color readings 

 were made by comparison with per- 

 manent standards, or from an 

 electrophotcmeter calibrated 

 against peimanent standards. Pre' 

 cipltated interferring substances 

 were removed by filtration or by 

 centrifugation . 



e. Sulfates - the turtidimetric 

 method was used by precipitating 

 the sulfate ion with the barium 

 ion in acid solution. Turbidity 

 values, converted to p. p.m. of 

 sulfate ion, were read from a 

 Hellige turbidimeter calibrated 

 against standard sulfate solu- 

 tions . 



f . Total solids - 100 ml. of sample 

 was evaported to dryness over a 

 water bath, dried for at least 

 one hour at 103* C, and weighed. 

 Total solids and dissolved solids 

 will have about the same value 

 for nearly all stations where 

 turbidities were low. 



Samples for element analysis were 

 periodically sent to a commercial labora- 

 tory set up for this type of analytical 

 work. The elements they tested for and the 

 methods used were as follows: 



a. Iron - Thiocyanate method, refer- 

 ence (19). 



b. Copper - Carbonate procedure, 

 reference (19). 



c. Zinc - "Colorlmetrlc Deteimina- 

 tioDB of Traces of Metals" by 



