712 Notice on the Ferruginous Spherules. [July, 



a finer one in a gray impalpable powder, which being examined before 

 the blowpipe is silica with oxide of Iron. 



There is no trace of any thing like organic arrangement, such as cells, 

 &c. which are rarely completely obliterated in fossil fruits, how com- 

 plete soever the mineralisation of the substance of the fruit may be. 



The strongest proof however to my mind that they are not fossil fruits, 

 but originally ferruginous spherules, whether formed by volcanic action 

 (or by that which produces the pisolitic iron ores ?) arises from the 

 matrix in some of the specimens being almost wholly destitute of iron ! 

 and the spherule having evidently given iron to it, round its place, in 

 which when detached it leaves a coating of peroxide of iron which 

 stains the sandstone. Now if the spherule had been originally a fruit, 

 it must have obtained its iron from the sandstone itself or from filtra- 

 tion through it, which would have stained it, for we know of no colour- 

 less solution of iron like those of silex and lime, which may pass through 

 a rock and be deposited in bodies for which they have an affinity 

 without leaving coloured traces of their passage. 



One which I fractured contained a nucleus, excentrically situated, of 

 coarse sand, as if it had been inclosed in a globule of molten iron. 



This spherule weighed 33 grains and gave by muriatic acid approxi- 

 matively as follows : 



Of coarse silica, 16 grs. 



Fine impalpable powder of silica with some iron,. . 4 

 Oxide of Iron, 13 



33 



I am therefore still inclined to think these spherules inorganic, and 

 that they have been suddenly deposited in their present position as 

 ferruginous globules, but by what agency we cannot say. The amount 

 of sand in them would almost entitle them to be called ferruginous 

 sandstones. 



Mr. Darwin, in his recent work on South America, p. 123, describes 

 some ferruginous volcanic concretions, which are however fusible, as 

 from two inches to two feet in diameter ; their insides consisting of a 

 fine scarcely adherent volcanic sand or of an argillaceous tuff. He 

 quotes also D'Aubuisson (to whose work I have not the opportunity 

 of referring) as adverting to the tendency of iron to form hollow concre- 



