Chemical Analysis of Potable Waters. 213 



this effect ut the Dusseklorf meeting in 1883, and the opinion of this 

 committee accords with that of most sanitarians who have investigated 

 the subject. 



Secondly, it may be said that with the various means at present at our 

 command, waters which are very pure, chemically, of medium purity 

 and foul, may be distinguished, but whether these waters are there- 



and is' not to be decided by the analytical results. You may take a few 

 spoonfuls of the dejection of a typhoid-fever patient and add them to 

 a barrel of distilled water, and a chemical analysis will tell us that the 

 water is pure, and you may add a pound of healthy faecal matter to an 

 other barrel of distilled water, and an analysis will show that it is de- 

 filed, yet the first water may, if drunk, give rise to typhoid fever, 

 and the second to no harmful results at all. The analysis of water 

 is like that of air. It can show us the relative amounts of the main 

 and gross constituents, but the organized and living material which 

 may be present, and if so is probably most instrumental in producing 

 disease, can be neither recognized as such nor measured. In the ap- 

 pendix to the report of the Medical Officer of the Local Government 

 Board of Great Britain for 1881, is a report by Dr. Cory on the chemi- 

 cal examination of certain samples of water purposely polluted with 

 excrements from enteric-fever patients and other matters. Dr. Bu- 

 chanan sums up the result of the inquiry by saying: " While we must 

 ever be on the watch for the indications that chemistry affords of con- 

 taminating matters gaining access to our waters, we must (at any rate 

 until other methods of recognition are discovered) go beyond the labor- 

 atory for evidence of any drinking water being free from dangerous 

 organic pollution. Unless the chemist is well acquainted with the 

 origin and liabilities of the water he is examining, he is not justified 

 in speaking of a water as ' safe ' or ' wholesome ' if it contains any trace 

 of organic matter whatever; hardly, indeed, even if it contains abso- 

 lutely none of such matter appreciable by his very delixjate methods. 

 The chemist can, indeed, tell us of impurity and hazard, but not of 

 purity and safety. For information about these we must go, with 

 what the chemist has been able to teach us, in search of the condi- 



We are not, therefore, to infer that water analysis is useless because 

 in the present state of our knowledge there are many questions which it 

 cannot satisfactorily answer, for an analysis of a water may reveal to us 

 the presence of compounds which have doubtless resulted from the 

 decomposition of animal matter, as, for instance, in showing us that 

 a well is contaminated by leakage from a cess-pool or privy, or that a 



