150 PROCEEDINGS OF THE COTTESWOLD CLUB 



but unless much disturbed and peaty the Vyrnwy is 

 the clearer water, the river having a harder bottom of 

 sand, whilst the Severn, in places, has a soft alluvial 

 clay, which is, in fact, what gives the water its milkiness, 

 and which appears to be of the nature of China clay, or 

 Kaolin. The waters of both the Vyrnwy and the Severn 

 bear evidence of containing vegetable organic material in 

 considerable quantity from the commencement. Probably 

 it is peat, and the quantity of such vegetable material in 

 the main stream is largely added to by the highly-charged 

 waters of the Perry and Tern. The material of this kind 

 contained in the water of the Severn, where lower down 

 it comes to l)e used, is readily discovered on analysis by 

 the large amount of oxygen it is capable of absorbing 

 from permanganate of potash, it also gives a yellowish tint 

 to the water, much stronger at some times than at others. 



The chief characteristics of the waters of other tribu- 

 taries may be briefly mentioned. The Perry, Tern, and 

 Worfe are all off the Bunter beds, and contain similar 

 water excepting that the Worfe does not contain so much 

 of the brow^n-coloured vegetable matter as the other two 

 streams. They all three contain about the same amount 

 of solid material with a hardness of 24", i.e., they are 

 decidedly hard waters. Nearly half the hme that they 

 contain is sulphate of lime, which is sufficient of itself to 

 characterize them and the rocks from which they drain. 

 Of the three the Perry had the least degree of organic 

 purity on the day of collection of the water when all three 

 of the streams were full to the tops of their banks. 



The water of the river Stour gave signs of considerable 

 pollution. It contained a very appreciable quantity of 

 iron; in fact it was brown with iron oxide, no doubt 

 derived from the tin plate works. It also contained ex- 

 cessive quantities of sulphate and chloride evidently com- 

 bined with sodium in great part, and too much organic 

 material. 



