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less when manufacturers are doing nothing. In table “ B ” 
I give the percentage of volatile organic matter present in 
100 parts of the respective amounts of “total matter in 
solution.’’ By treating the analytical data in this manner a 
very fair opinion can be obtained as to the pollution of a 
stream like the Irwell. I have made similar calculations in 
regard to streams which were only polluted with what is 
known as “ domestic sewage,” and always found that the 
total matter in solution in the water contained from 27 to 
60 per cent of volatile organic matter; and, further, that 
this excessive amount of organic matter rapidly precipitates 
out on being exposed to the air. This precipitation of the 
organic “ sewage matter ” in solution is well illustrated in 
the analysis of the Irwell at Throstle Nest and the Irwell 
at Barton (in Table “ D ”). It will be seen, on calculating 
out the percentages, that the Irwell at Throstle Nest contains 
S7'5 per cent of volatile organic matter in 100 parts of its 
“ total matter in solution,” whilst at Barton the same water 
contains only 17'61 per cent of volatile organic matter in 
100 parts of its “ total matter in solution. Exactly one-half 
of the organic contamination has been precipitated out of 
the water in the flow from Throstle Nest to Barton, 
Eegarding the method of analysis of the waters, I may 
say that I consider Frankland’s process quite useless by itself 
in ascertaining the state of the pollution of a river in a 
manufacturing district, because it cannot discriminate 
between the pollution by sewage and the pollution by 
manufacturer’s waste waters. By adopting a parallel testing 
of the water by the processes of Wanklyn and Tidy, a very 
good idea is obtained of the state of the water, especially if 
these two processes are supplemented with the determina- 
tion of the amounts of chlorine, volatile matter in both 
“ suspended matter ” and “ matter in solution.” I always 
filtered the water, and considered the residue dried at 
