Botanical Society of Edinburgh* 231 



A recent discovery of the author, communicated to the Royal 

 Society of Edinburgh, has shown that fluorides are much more widely 

 distributed than is generally imagined, and that the trap rocks near 

 Edinburgh, and in the neighbourhood of the Clyde, as well as the 

 granites of Aberdeenshire, and the ashes of coal, contain fluorides, so 

 that the soils resulting from the disintegration of those rocks cannot 

 fail to possess fluorides also. All plants accordingly may be expected 

 to exhibit evidence of their presence in the following portions of their 

 tissues or fluids : — 



1 . In the ascending sap, simple fluorides. 



2. In the descending sap, in association with the albuminous vege- 

 table principles, and in the seeds or fruits, in a similar state of asso- 

 ciation, fluorides along with phosphates. 



3. In the stems, especially when siliceous and hardened, fluorides 

 in combination with silica. The investigation is still in progress. 



2. " On the presence of Iodine in various Plants, with some re- 

 marks on its general distribution," by Mr. Stevenson Macadam. 



The present paper owes its origin to some observations lately made 

 by M. Chatin of Paris, and communicated by him to the French 

 Academy of Sciences. 



Chatin is of opinion, that in the atmosphere, in rain-water, and in 

 soils there is an appreciable amount of iodine ; that the quantity of 

 this element present in one district difl^ers from that in another ; and 

 that the relative amount of iodine in any one locality determines to 

 a great extent the presence or absence of certain diseases. For in- 

 stance, in the district of country which he classifies under the general 

 title of the " Paris zone," the quantity of iodine present in the atmo- 

 sphere, in the rain-water, and in the soil is comparatively great, and 

 to this he ascribes the absence of goitre and cretinism ; whereas in 

 the zone corresponding to that of the '* alpine valleys," the amount 

 of iodine has diminished to one-tenth of that found in the " Paris 

 zone," and to this scarcity of the element he attributes the prevalence 

 of goitre and cretinism, which in that zone are endemic. Considering 

 that the subject was one of great importance, more especially if the 

 conclusions arrived at by Chatin (in reference to the functions fulfilled 

 by iodine in preventing the occurrence of the diseases referred to) 

 could be legitimately deduced from the experiments which he per- 

 formed, the author has this summer undertaken a series of analyses 

 in reference to the general distribution of iodine. Mr. Macadam's 

 researches have as yet been mostly directed to the atmosphere and to 

 rain-water, and he considered that a notice of the results obtained 

 might be interesting to the Society, alike from the intimate connexion 

 which exists between the plant and the atmosphere, and from the 

 fact, that he has been led to seek, and to detect, the presence of 

 iodine in a department of the vegetable kingdom in which it has not 

 hitherto been observed. 



Chatin has not published a detailed account of the processes adopted 

 by him ; but from the manner in which he speaks of the good effects 

 produced by the addition of potash to substances under examination, 

 which, to use his words, " arrested the complete decomposition of the 



