Northumberland and Durham. 



51 



I have now concluded the most important of the geological 

 observations I had to make upon the Coal-field, and it remains only 

 to give some account of the mineral springs that occur within its 

 limits, and of the deleterious gases to which the mines are subject. 



The mineral springs have been found either bursting out at the 

 surface, or have been discovered in the shafts of mines, and in the 

 dykes that intersect the strata. Those impregnated with common 

 salt have been noticed in the pits at Walker, Wall's end, and Percy 

 main, and in most of the deep mines between Newcastle and Shields : 

 on the Wear they have been found at Birtley and Lumley-thick, 

 and appear rising to the day at Ouston 1 mile west of Birtley, and 

 at Butterby near Durham. 



The spring at Walker issues into a deserted shaft from a bed of 

 slate-clay at the depth of 55 fathoms ; but being dammed up rises 

 33 fathoms higher to within 22 fathoms of the surface, and 15 

 fathoms of the level of the Tyne. It is pumped from a reservoir in 

 the pit for the manufacture of soda, the salt obtained in the inter- 

 mediate process being exempted by an Act of Parliament from the 

 salt duty. The following is the analysis of this water by Mr. G. 

 Woods. 



Contents in 1000 grains of water. 



Dry muriate of soda 



Dry muriate of lime 



Muriate of magnesia 



Carbonate of lime . 



Carbonate of iron . 



Silica 



32 

 10 



1 

 I 



A little carbonic acid gas. 

 G 2 



43 grains 



