ON THE AIR AND WATER OF TOWNS. 7l 



decomposing a little of the soap used to test for hardness. These waters 

 came out of the inorganic strata direct : the difference in this respect may- 

 be seen by the following specimens : — luorganic matter 



in a gallon. Hardness. 



Drain 4<-feet deep, near Manchester 8-4 4--2 



Another on the higher grounds, less cuiti- "1 ^.g g.^^ 



vated land and shallow drain J 



Another on bog-land 7* 3*75 



Water near the soil .... - SO'S , Y'*? 



Well at Stretford near Manchester, badly- "1 ^q, j^.22 



drained garden land « J 



, another near it 29'7 15*5 



Thames at London Bridge 29-06 15*5 



From an underground street-cistern 4a'05 15-5 



Thames at Oxford 17-25 16- 



Thames at Seven Springs 12-25 12*75 



Thamesat Andover Ford, 13-3 13-88 



Hl<'her up the river the extraneous salts diminish as well as the ashes of 

 the organic substances. The best-drained land (the first two) has very little 

 in excess, but the badly-drained land has a great deal in excess. Tiie under- 

 ground cistern, with many impurities, may be looked on as water of very badly- 

 drained land, and is the worst ; it was taken from a court in London. There 

 mifht be many instances given of the same kind from wells and elsewhere. 

 If we take the excess of inorganic matter over hardness, we shall have: — 



Excess of inorganic matter over hardness . 

 grs. per gallon. 



4 foot drain 4<-2 



Shallow drain in poor land 1'85 



Bog-land drain 3"25 



Water near the soil 22-33 



Stretford, 1st 8-72 



Stretford, 2nd 13-2 



Thames, London Bridge 17* 



Cistern in London (underground) 27-55 



Thames, Oxford 1'25 



Thames, Seven Springs. , 0*5 below. 



Thames, A ndover Ford 0-58 minus. 



Thames, at Kemble '6 above. 



Chelsea, filtered 8-528 



Windsor 6-51 



New River 6-46 



Apparently then the difficulty of obtaining water free from impurity in- 

 creases as we go down a river, and as we come to cultivated land. The deep 

 drain-water of cultivated land, although having more inorganic matter, is 

 not in other respects to be objected to. I have several specimens, which, 

 after standing a long time, have deposited organic matter only in very minute 

 quantities, and are in fact equal to well-water of considerable depth. The 

 organizable matter seems to have been removed, although the organic 

 matter is not entirely removed, the only thing remaining being some of the 

 highly carbonaceous compounds of the soil. Its superiority over river-water, 

 which consists often of drainage water from the mere surface, cannot there- 

 fore be questioned, except when the river-water itself is composed of the 

 under-drainage of a country, or the drainage of such barren tracts as give off 

 little organic matter, or readily part with it. 



