150 



The chief impurities found in drinking waters, as detected by chemical analysis, 

 are of an organic nature, and arise from the presence of decomposijig animal or 

 vegetable matter, or both. The former is to be regarded as the more deleterious of 

 the two, and comprises the solid and fluid excreta of animals, decaying animal mutter 

 and the like ; vegetable pollution consists of peaty matter — the more or less decom- 

 posed remains of plants. Although vegetable matter is not as injurious as that of 

 animal origin, an excessive quantity is very apt to cause diari'hoea and kindred 

 complaints. 



Whether the organic matter itself always acts in the water as a poison or not 

 is yet a question open for discussion, though there seems to be ample evidence that 

 in many instances active organic poisons are developed by the decomposing matter. 



It has, however, been well established that it is the organic matter of a water 

 that forms the food for the growth of bacteria — microscopicplants, among which are 

 the disease germs — and cases of typhoid (a germ disease) have been repeatedly tiaced 

 to drinking water surcharged with organic matter. 



For these reasons we may safely conclude that a water containing much oj-ganic 

 matter must be more dangerous to health than water comparatively organically 

 pure. 



It is of the first importance, therefore, to discover the degree to which any 

 water may be contaminated by oi-ganic matter and to endeavour to establish whether 

 such be vegetable or animal. 



The amounts of free and albuminoid ammonia, of the oxj^gen absorbed in fifteen 

 minutes and four hours, and of chlorine, are a measure of the organic impurities of a 

 water. 



Large quantities of free ammonia associated with a considerable amount of 

 chlorine prove contamination with sewage. 



Small quantities of free ammonia and chlorine and high amounts of albuminoid 

 ammonia and " oxygen absorbed " indicate vegetable pollution. 



When the ratio of oxygen absorbed in 15 minutes to that absorbed in 4 hours is 

 as 1:2 dissolved vegetable matter is indicated ; when this ratio approaches 1:1-5 the 

 presence of animal organic matter is shown. A water contaminated with vegetable 

 matter will absorb or use up more oxygen than one polluted with animal matter. 



As GVGvy water must be judged according to its source and surroundings, it is 

 impossible to lay down rules that could be applied rigidly in every case, though it 

 has been abundantly shown that a good water, wholesome for use, should not contain 

 more than '08 parts per million of free ammonia, nor more than -10 parts per million 

 of albuminoid ammonia, and the amounts of chlorine and total solids should not 

 exceed 70 and 570 parts respectively. 



Those who are about to dig wells are cautioned against locating them in barn 

 yards and stables or near any source of pollution — and this is especially urged where 

 the soil is sandy or gravelly. It has been proved beyond dispute that the soakage 

 from such contaminating sources will travel comparatively long distances in light soil, 

 and it is in such that it will act as a cesspool. 



The surroundings of the well should at all times be kept clean, and the well 

 itself examined fioni time to time as to its freedom from refuse material. Vegetable 

 debris and dead animals are often the cause of impure water. 



FOUNDATION COMB. 



In June last we were requested by the D. A. Jones Company Limited, of Beeton, 

 to analyse and repoi-t on sevei-al samples of" foundation comb," which they suspected 

 to be adulterated. As the matter was deemed of great importance to bee-keepers 



