412 Report of the Commissioners on the 



from the bottoms of the ships, we likewise obtained, with a view 

 to inquire into the truth of this opinion, portions of water from 

 the dock, taken at three diflferent depths from the surface. 



In order to ensure the subjecting of all these various specimens 

 to the most careful and rigid examination, upon one uniform sys- 

 tem, we put them, for that purpose, into the hands of Dr. Bostock, 

 a gentleman eminently qualified for the task by his extensive 

 knowledge of chemistry, and his practical experience in this 

 department of analysis. In the Appendix will be found the detailed 

 account of his examinations, in the accuracy of which we have 

 every reason to repose the fullest confidence. In his report to us, 

 he justly remarks that it would have required a much longer 

 space of time than was allowed him, to have performed a com- 

 plete scientific analysis of so many specimens of water ; but the 

 results he obtained are quite sufficient for the object pro- 

 posed, and to which we more particularly directed his attention, 

 namely, " to ascertain how far the water of the Thames, conti- 

 guous to, or in the neighbourhood of London, is in a state proper 

 .for being employed in diet and various other domestic purposes/' 



The general conclusion he deduces from the whole series of 

 examinations is expressed in the following passages of his report : — 



" It appears that the water of the Thames, when free from 

 .extraneous substances, is in a state of considerable purity, con- 

 taining only a moderate quantity of saline contents, and those of 

 a kind which cannot be supposed to render it unfit for domestic 

 purposes^ or to be injurious to the health. But as it approaches 

 the metropolis it becomes loaded with a quantity of filth, which 

 renders it disgusting to the senses, and improper to be employed 

 in the preparation of food. The greatest part of this additional 

 matter appears to be only mechanically suspended in it, and sepa- 

 rates by mere rest. It requires, however, a considerable length 

 of time to allow of the complete separation; while, on account of 

 its peculiar texture, and comminuted state, it is disposed to be 

 again diffused through the water by a slight degree of agitation, 

 while the gradual accumulation of this matter in the reservoirs 

 must obviously increase the unpleasant odour and flavour of the 

 water, and promotes its tendency to the putrid state. - 



" Regarding the greatest part of the extraneous matter in the 

 Thames as mechanically mixed with it, we may conceive that a 

 variety of incidental circumstances will affect its quality in the 

 same situation and under the same circumstances of the tide ; but 

 the observations are sufficiently uniform to warrant us in con- 

 .cluding, that the water is in the purest state at low tide, and the 

 most loaded with extraneous matter at half ebb. It would appear, 

 however, that a very considerable part, if not the whole, of this 

 extraneous matter may be removed by filtration through sand, 

 and still more effectually by a mixture of sand and charcoal." 



The examination of the water taken from the London Dock, 

 showed that it did not contain the smallest appreciable quantity 

 of copper. 



