130 HEALTH AND DISEASE 



ascertaining what constituents are present which may exercise any injurious 

 action on the animal which drinks it. 



By the mere physical examination the general character of the water is 

 'determined by the unaided eyesight, but it must be understood that this 

 kind of examination does not justify any conclusion as to the qualities of 

 the water which may render it fit or unfit for use. It has been proved that 

 :some of the brightest water may be charged with deadly material. In one 

 of the outbreaks of cholera which occurred in London, a certain pump, to the 

 water of which several serious outbreaks of cholera were traced, was so noted 

 for its bright, and sparkling, and palatable character that all the people 

 within a reasonable distance round it came regularly to obtain, at any rate, 

 .sufficient water for drinking purposes, and as a consequence the disease 

 was widely spread. As a matter of course, as soon as the character 

 of the water was discovered, the pump was closed, and the spreading of 

 cholera from that source was arrested. An illustration in the opposite 

 direction was afforded by an examination of the porter -coloured water 

 which is so commonly noticed in ponds near straw-yards, such ponds being 

 the ordinary drinking-places for horses and cattle. The brown-coloured 

 water is commonly said to suggest the presence of sewage, but the water 

 referred to in the farm ponds was repeatedly examined by Dr. Augustus 

 Voelcker, and found by him to be singularly free from organic contami- 

 nation, the brown colour being due to the formation of humic and ulmic 

 acids which did not appear to exercise any deleterious influence on the 

 animals which drank of it. There can be no doubt that the water of these 

 farmyard ponds, into which the drainage from the straw-yards is constantly 

 running, must have received large quantities of organic matter; but, being 

 -at the same time perfectly open to the constantly moving atmosphere, the 

 organic matter must have been oxidized into comparatively innocuous com- 

 pounds. 



It is not suggested, of course, that porter-coloured water is a desirable 

 fluid for horses or cattle, nevertheless it is an undoubted fact that it was 

 in former times the habitual drink of those animals year by year; and in 

 one case in the writer's knowledge it continued for a dozen years on a large 

 farm, where the stock remained during the whole of that time in a remark- 

 ably healthy condition. It was during this period that the two circum- 

 stances, i.e. the remarkably healthy condition of the stock on the farm and 

 the habitual use of porter-coloured water for the horses and cattle in the 

 case of the latter the invariable use of it for the reason that there was no 

 other water within the animals' reach, attracted Dr. Voelcker's attention 

 and led to the analyses referred to. The story itself suggests that a 

 chemical examination of discoloured water is necessary in order to deter- 



