258 ANNUAL OF SCIENTIFIC DISCOVERY. 



Company, as compared with the Lambeth, was as seven to one; according 

 to the most favorable vic\v of the case, as given by Mr. Swain, it was three 

 and one-half to one. There is nothing to account for this difference but the 

 larger quantity of organic impurity in the water supplied by the Vauxhall 

 Company, which still obtains water from the more impure source. The out- 

 break of cholera in the Golden-square district, in September 18-34, was traced 

 to the pump in Broad Street, which was subsequently found to have commu- 

 nicated with the drain of a neighboring house. 



Organic matters in standing water undergo a kind of fermentation, by 

 which carbonic acid, sulphuretted hydrogen, and other gases, are got rid of, 

 and nitric acid is formed The water thus undergoes a process of self-purifi- 

 cation. This occurred in Thames water, and accounts for the fact that ships 

 were often supplied with water from the Thames below London Bridge. 

 This water is dangerous to drink before or during the fermenting process. 



The appreciation of small quantities of organic matters by chemical pro- 

 cesses is a difficult process. During the evaporation of water, the organic 

 matters are dissipated, and not all left in the evaporating basin. 



The microscope is an important aid. It detects the nature of organic im- 

 purities. These consist of dead and living animal and vegetable njatters. 

 The dead consist of the tissues of animals and plants. The source of these 

 impurities can in some instances be made manifest. Such impurities are 

 very manifest in the Thames and surface-well waters, scarcely to be detected 

 in the deep-well waters. The living matters consist of plants and animals. 

 The filaments of microscopic Fungi have been found in impure well-water. 

 They have been detected in several waters known to be productive of dis- 

 ease. Amongst the living animals, the forms of Infusoria are most abundant. 

 These are frequently indicative*Df the impure condition of water. Eggs of 

 the higher animals are not unfrequently found in the Thames water; and 

 some of these undoubtedly belong to those forms of Annulosa, which find 

 their highest development in the human body. 



Many of these forms of animal and vegetable life arc not injurious in 

 themselves; but they are most numerous where there is the greatest amount 

 of impurity, and are a measure of the greater or less objectionable nature of 

 a water for drinking purposes. 



PURIFICATION OF WATER CONTAMINATED WITH LEAD. 



Professor Faraday, writing to the London Times, on the danger of drink- 

 ing rain-water contaminated with lead (dissolved from the lead of roofs), 

 states, that if some powdered chalk or whiting be put into the cistern in 

 which such water is collected, and be stirred immediately after rain, the 

 water may, with the greatest facility, be obtained in a perfectly fit state for 

 all culinary and domestic purposes. The lead is rendered insoluble, and the 

 water may be filtered or left to settle. 



EFFECTS OF THE PREPARATION OF LEAD UPON THE INFERIOR 



ANIMALS. 



A. M. Pe'cart-Taschereau, a litharge manufacturer (Deutsche Klinik}, has 

 investigated, with some care, the effects of the preparations of lead upon the 

 inferior animals. Strange as it may seem, he soon noticed that the Dog is 

 never affected with symptoms of lead poisoning. He has seen this animal 



