268 Ur. A. Voelcker on the Composition of 



sess the power of separating from sea-water the compounds of 

 iodine and condensing them in their tissue, without any detri- 

 ment to their healthy function. In the same notice the author 

 states that soda was more abundant in the specimens of Armeiia 

 maritima grown on the sea-shore, and potash prevailed in those 

 grown in the inland higher places of Aberdeenshire. 



The plants which I used for ash-analyses were grown in the 

 neighbourhood of Edinburgh, and collected when in flower in 

 the month of June ; roots, leaves, and flowers were burned 

 together. 



No. 1. Ash of specimens grown close to the sea-shore and 

 dui'ing high water exposed to the sea-spray. 



No. 2. Ash of specimens grown on an elevated, partially de- 

 composed trap-rock opposite the former locality. 



No. 3. Ash of specimens grown in Mr. Lawson's nursery near 

 Edinburgh, upon light sandy soil. 



No. 4. Ash of specimens grown in the Scottish Highlands. 



Dr. Dickie^s experiments I found peifectly confii'med by my 

 own. With the exception of those specimens which wei'e exposed 

 to the sea-spray, the examination for iodine of Armeria maritima 

 grown in other localities, gave me negative results ; and a compa- 

 rison of the composition of the ash of No. 1 and 2 likewise proves 

 the correctness of Dr. Dickie's statement respecting the preva- 

 lence of soda or potash. 



1 endeavoured to determine the quantity of iodine in the ash 

 of specimens of Armeria grown near the sea-shore ; but though I 

 used large quantities of ash, I had to give up the attempt on 

 account of the minute quantity of iodine present in the ash. 



The iodine reaction made with large quantities of ash, com- 

 pared with the much more intense blue colour which a much 

 smaller quantity of the ash of sea-weed produces with starch, 

 renders it evident, that the proportion of iodine in the ash of 

 Armeria maritima amounts to mere traces ; and I am inclined 

 therefore to difi^er from Dr. Dickie's conclusion in ascribing to 

 this plant a power of separating from the sea-water iodine com- 

 pounds and condensing them in its tissue — a power similar to that 

 possessed by marine Algae. The power which marine Algae pos- 

 sess of extracting iodine from sea-water appears to me altogether 

 diff'erent : iodine is an essential element for the healthy condition 

 of sea-weeds ; without it these plants cannot exist, and hence we 

 can well imagine that their peculiar organism possesses a power 

 of extracting iodine from sea-water, of assimilating the same, and 

 perhaps of storing it up. Armeria maritima on the contrary does 

 not require iodine as a necessary element, and grows equally well 

 in a soil destitute of iodine as on the sea-shore. I am therefore 

 inclined to ascribe the occasional presence of iodine in Armeiia 

 maritima, not to a power similar to that possessed by marine 



