252 Mr. A. B. Northcote on the Water of 



salt-deposits which that system contains, it becomes evident that 

 the constituent added in largest quantity must be chloride of 

 sodium ; and from the analyses which follow it will be seen that 

 at almost all ordinary times this salt constitutes from three- to 

 four-tenths of the entire solid residue. That no portion of this 

 salt can be derived from admixture with sea-water is obvious; 

 for in addition to the existence of numerous locks upon the river, 

 the length of the Severn below Worcester is 68 miles, if King 

 Road be taken as the point at which it falls into the Bristol 

 Channel. 



The Severn for some distance both above and below Worcester 

 has cut for itself a deep channel in the Red Marl through which 

 it flows ; and from the softness of its high banks, a slight rise in 

 the level of the river is sufficient to render the water turbid. 

 Dr. Nash, in his ' History of Worcestershire/ written in 1781, 

 deduces the river's name from this circumstance. " The Severn/' 

 he says, " in Latin Sabrina, is so called from Sabr sand, Sabrin 

 sandy*, because this river is often muddy, especially when hasty 

 rains come from the Welsh mountains/' Since the time at 

 which this was written the increased navigation and the employ- 

 ment of small steamboats upon the river must have augmented 

 this turbidity ; and from the well-known persistence with which 

 clayey matters remain suspended in liquids, it can occasion no 

 surprise that the water of the Severn at this part never clears 

 beyond opalescence. Of this suspended matter I have examined 

 two portions, collected just below the surface in midstream: — one 

 from water taken on the 12th of April, 1866, from the imme- 

 diate neighbourhood of the waterworks, when after some days of 

 comparative clearness the river became suddenly turbid; the 

 other from water taken from a different and higher part of the 

 river, nearly four miles above Worcester ; this was collected on 

 the 14th of February, 1867, after the subsidence of the flood 

 which followed the melting of last winter's snow, and when the 

 river had just withdrawn within its banks. These are therefore 

 specimens of detritus formed under extreme conditions; and the 

 similarity of their composition is very striking, no greater differ- 

 ence occurring than I have found to exist between the deposits 

 formed in two bottles which were filled consecutively from the 

 same part of the river. In analyzing these sediments, after 

 drying at 140° C, they were digested with warm and very dilute 

 chlorhydric acid for about an hour : the amount of its solvent 

 action will be seen below, and may be taken as in some sort re- 

 presentative of the effect which a body of water aided by carbonic 

 acid would exercise upon the suspended matter. It is worthy of 

 remark that the whole of the organic matter of the sediment ap- 

 * Quoting Bullet, Dictionnaire Celtique. 



