APPENDIX. 385 



generally exists in the form of a hydriodate ; I then added a solution of chlorine 

 in water, to decompose the hydriodic acid, without obtaining the faintest indica- 

 tion of iodine. If hydriodic acid had been present when the chlorine water was 

 added to the solution, a blue band (the iodide of starch) would have been per- 

 ceptible at the junction of the two fluids, — the chlorine uniting with the hydrogen 

 of the hydriodic acid to form muriatic acid, and the iodine with the starch. This 

 plan of testing for iodine was pointed out by M. Balard, and is, I think, the best 

 method of detecting small portions of iodine. As I repeated it several times with 

 slight variations, I am inclined to think that iodine does not exist in the brine in 

 any form. With regard to bromine being present in the brine, I cannot speak so 

 positively. I only know of two methods, both of which I tried, but without obtain- 

 ing the slightest trace of any thing like bromine. It usually exists as ahydro- 

 bromate. When a stream of chlorine is transmitted through a fluid containing 

 it, the hydrobromic acid is decomposed, the chlorine and hydrogen combining, and 

 the bromine being disengaged, imparts a yellow colour to the fluid, and by ex- 

 posing it afterwards to heat, the bromine distils over, and may be collected in 

 a receiver. This is the mode of obtaining it from bittern. The other mode is to 

 shake sulphuric ether with the fluid after the chlorine has been passed through 

 it ; the ether dissolves bromine, and when it is left at rest it collects at the top, of 

 a rich hyacinthine colour. 



Believe me always, your's, very truly, 



JOHN THOMSON. 



APPENDIX, E. 



I find by subsequent inquiry that I have been misled respecting the surface level 

 of Droitwich and Stoke Prior ; therefore the inference that the first bed of rock- 

 salt is on the same level at these places is incorrect. The facts are these — 

 Depth to Droitwich brine 170 feet. Depth to Stoke brine 300 feet. 



Difference of surface levels between ? ^ ^c 

 Stoke and Droitwich § 



275 Leaving 25 feet difference, 



between the depth of the 



brine at the two places, 



instead of its being at the 



■ same level. 



APPENDIX, F. 



Rise of the Ground from the Water at Chapel Bridge, Droitwich, to the summit 

 of Rashwood Hill ; also from the same place to the entrance at Witton. 



Ft. In- 



1st. Length from the Water to Hill-end Gate 255 yards. Rise 32 10 



2nd. Ditto from Hill-end Gate to Leather Bridge 574 Falls. 



3rd. Ditto from Leather Bridge to Ford Gate 471 Rise 20 3 



4th. Ditto from the Ford Gate to the summit of the ) cr»o t>- an n, 



Hill near Mr. Gossage's ] ^^^ ^''^ ^^ ^ 



Total length 1908 122 10 



Deduct fall from Hill-end Gate to Leather Bridge 7 2 



Total rise 115 8 



1st. Length from Chapel Bridge to Cook's Corner 190 yards. Rise 12 7 j 



2nd. Ditto from Cook's Corner, at the entrance of the \ 



Worcester Road, to near Smith's Garden, V 494 Rise 34 6 



at the bottom of Witton HoUoway ) 



3rd. Ditto from Smith's Garden to the Gate at Witton.. 354 Rise 31 9^ 



Total length 1038 78 11 



N. B. The water at Leather Bridge is about 21 feet higher than at Chapel Bridge. 



