On the occurrence of Metallic Iron in Fossil Wood. 333 



ill the experiment just described. By increasing, if necessary, 

 the length of the U-tubes, it would not be difficult to collect 

 from 0-5 to 1 grm. (7 to 14 grains) of water from the air in periods 

 of an hour, or even half an hour ; and thus the amount of aqueous 

 vapour might be determined accurately to j^odtli part of the 

 whole quantity, instead of an uncertain approximation to }th or 

 y'yth of the same, which is perhaps all that can be attained by the 

 methods now generally in use. 



Queen's College, Belfast, 

 Sei)tember 28, 1852. 



LII. On the Occurrence of Metallic Iron in Fossil Wood. 

 By W. G. Lettsom, Esq. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, Madrid, Sept. 23, 1852. 



TN the recent edition of Phillips's Mineralogy by Messrs. 

 A Brooke and Miller, at page 685 mention is made of the 

 discovery of metallic iron in certain metamorphic rocks in Antrim 

 by Dr. Andrews of Belfast ; and as this fact is a novel one, per- 

 haps the following account of the occurrence of this substance in 

 a metallic state in Sweden, translated from a periodical which 

 appears here under the title of El Restaurador Farmeceutico, may 

 be thought worthy of a place in the pages of the Philosophical 

 Magazine. 



M. Bahr, a pupil of Prof. Svanberg, has had occasion to ana- 

 lyse the fossil wood derived from an island in the lake of Ralaug 

 in Smaland, whose composition resembled that of the mineral 

 known by the name of limonite. 



On endeavouring to pulverize this mineral in small quantities, 

 he observed some minute tenacious grains which yielded but very 

 little to the action of the agate pestle. These grains were simply 

 metallic iron ; they became flattened by the blow of a hammer, 

 were attracted by a magnet, and were soluble in acid with evo- 

 lution of hydrogen. 



M. Bahr enters upon the question, whether this iron had been 

 formed in the mass of this wood by the reduction of some soluble 

 salt of iron, or whether it has been originally introduced in the 

 form of a nail, or the fragment of some tool or instrument, 

 which, after having been partially destroyed by oxidation, may 

 nevertheless have left some traces of its presence in ..the metallic 

 state. 



After having examined and discussed with care the origin, 

 characters, structure, and composition of the specimen of fossil 

 wood in question, M. Bahr arrives at the conclusion that the 



