WATER ANALYSIS 57 



Examination of a Sample. 



Equal quantities are taken every hour and mixed, and a 

 sample is then taken. This is examined for the following 

 constituents and characteristics. The bottle containing the 

 sample should be completely filled, and examined at once 

 or kept in an ice chamber. 



Chlorine. Dilute with as much distilled water, and 

 examine as in water analysis. 



Ammonias. In a crude sewage or unfiltered effluent, 

 5 c.c. should be diluted to 500 c.c, but in a good effluent a 

 dilution of ten times will usually be sufficient. Test a 

 little with Nessler, and judge from coloration produced. 



Oxygen Absorption. Dilute ten to one hundred times, 

 and be careful to watch for decolorization of the perman- 

 ganate, as several lots may be needed. 



Nitrates and Nitrites are estimated as in water ; but as 

 seen in the table above, nitrates may be present in large 

 amount, especially in a good effluent, and the coloration 

 produced will be much stronger than that in the standard. 



Suspended Solids can be estimated by filtering a known 

 quantity of the sample through a weighed filter paper, and 

 drying and weighing again. The filter paper is then 

 ignited in a weighed platinum or other crucible, which is 

 cooled and weighed. The increase in weight of the crucible, 

 less the weight of filter-paper ash, gives the mineral -content 

 in the suspended solids. The loss or difference between 

 the total and the mineral part is the amount of organic 

 matter in suspended solids. 



Dissolved Solids are estimated in the filtrate. 



Incubator Test is a test for putrescibility laid down by 

 the Mersey and Irwell Joint Committee for effluents dis- 

 charged into the Manchester Ship Canal. The effluent is 

 tested in the fresh state for oxygen absorption in three 

 minutes. A bottle is then completely filled with the 

 sample, stoppered, and incubated at 8o F. (27 C.) for a 

 week. The contents are thereafter tested for oxygen 

 absorption in three minutes. If the amount absorbed is 

 the same or less, the effluent is considered harmless as 

 regards its power of absorbing oxygen from any stream 

 or river into which it may be poured. If the oxygen 



