of Iodine in Spring Water. 1 1 



that I have found traces of iodine not only in warm and saline 

 sprincTs, but also in every common spring in which there are 

 traced of the chlorides of calcium and sodium. It appears 

 that Mr. Murray had, previous to Prof. Daubeny's communi- 

 cation, ascertained the existence of iodine in the Gloucester 

 and Cheltenham springs ; also in the saline waters at Ingestre 

 and at Bex. Iodine appears to exist in the warm sprmgs ot 

 Keddleston, Matlock, Buxton, wells near Bristol and Bath ; 

 the quantity is so small as not to be appreciable, and requues 

 the evaporation of many gallons before the slightest change 

 is induced by the amylaceous test. Sir H. Davy attributed 

 the colouring principle in sea-water partly to the presence of 

 iodine ; as the chloride of sodium is so generally diffused and 

 iodine appears to be an accompanying principle, and therefore 

 probably may be traced in every spring. The strongly charged 

 saline springs of Cheshire contain it in much larger proportion 

 than the warm springs above mentioned; and in all the well-wa- 

 ters I have examined, by the evaporation of fifty or sixty gallons 

 to a few ounces, a faint peach-blossom colour is produced by 

 the test. I evaporated fifty-four gallons of the condensed 

 water of a steam-engine in the neighbourhood where I re- 

 side, and which may be considered as nearly equal to distil- 

 led water in purity ;— no traces appeared, and therefore, inde- 

 pendent of the vessels employed in the evaporation, iodine, as 

 to its state of combination, I have not been enabled to detect. 

 The quantity existing in every mineral water is too minute to 

 produce any effects on the constitution, and therefore, the as- 

 certainment of its existence may be considered more as inter- 

 esting to die chemical inquirer than of any practical utility *. 

 Thus silex and alumina have been stated as existing in some 

 warm springs. Unless there is an uncombined alkali in the 

 waters, I have never discovered either the one or the other. I 

 believe the error has arisen from very finely divided silex, or 

 alumina, when diffused in water, requiring many days for its 

 deposition ; and hence, previous to the analysis of any mineral 

 water, it should be preserved in a quiescent state many days, 

 in order to admit of the deposition of every particle of matter in 

 a state of mechanical suspension. And 1 perfecdy accord with 

 the observations of the late Dr. Murray of Edinburgh, that 

 the salts ought to be considered as existing in the \yaters m 

 their natural state, in that state of combination in which their 



* The continued or frequent exhibition, however, (to use a medical 

 phrase) of waters containing even such minute proportions of lodnie, niay, 

 we conceive, at length produce appreciable and perliaps important ettects 

 upon the system ; and in this point of view tiie subject of Dr. Hendersons 

 paper may become practically useful. — Edit. 

 ' ' ^ ' C 2 solubility 



