Mr. Binney on Fossil Trees near St. Helerts. 165 



pole. On this it was observed 1 , that the iodine would form 

 iodic acid with the ox3'gen coming from the starch solution in 

 the opposite direction, and so not appear in a free state. I 

 answer, if so, why did not the iodine ultimately appear at the 

 negative pole, and there affect the starch, seeing that the 

 newly-formed iodic acid would be as liable to direct decom- 

 position as the original? Again, if bromide of iodine was di- 

 rectly decomposed, why was there effervescence at the -positive 

 pole, and why was not an orange compound of bromine and 

 starch formed at that pole ? 



Analogous views are applicable to the decomposition of the 

 hydracids, and were formerly sufficiently explained*. 



As to the observation on my argument for the solution of 

 haloid salts as hydracid salts, that the acid and alkali formed 

 in the circumstances mentioned f might have arisen from the 

 union of the elements of the haloid with those of water, it is 

 plain that this view assumes that haloid salts, supposing them 

 to be dissolved as such, are directly decomposed by the cur- 

 rent, whereas it was established by evidence of exactly the 

 same kind, as in regard to hydracids, that the electro- nega- 

 tive element appearing during their decomposition has a se- 

 condary origin. But further, supposing this had not been 

 established, on what grounds can we assume that if the haloid 

 is dissolved as such, and directly decomposed, the hydracid 

 supposed to be formed by the subsequent union of the elec- 

 tro-negative element with hydrogen shall not be equally di- 

 rectly decomposed ? and if so, how can we have any acid to 

 detect, far less a constantly accumulating quantity of it ? 



St. Andrews, January 27, 1844. 



XXVII. On the remarkable Fossil Trees lately discovered 

 near St. Helen's. By E. W, Binney, Secretary of the 

 Manchester Geological Society \. 



PROBABLY no fossil plant has excited more discussion 

 among botanists than the Stigmaria. It is the most com- 

 mon of the whole number of plants found in the coal measures, 

 but there has hitherto been the greatest uncertainty as to its 

 real nature. In the Lancashire coal-field traces of it may be 

 found in every mine. It abounds in all the floors of the coals 

 unmixed with any other plants, and having the long stringy 

 fibrils hitherto considered as leaves radiating from the stem 

 in all directions, and often the fibrils alone are seen without 



* See p. 246-7 of the memoir in this Journal above referred to. 

 t See p. 357, &c. 



X Communicated by the Author; having been read before the Man- 

 chester Geological Society, October 26, 1843. 



