Mr. Way 07t a Spat?iic Carbonate of Iron, 129 



may be true, as has been suggested bv Von Buch, that the 

 very prismatic form which belongs to pnosphate of lime as a 

 mineral species, adapts it for the fibrous structure of bone 

 better than other earthy compounds in which the axis of cry- 

 stallization is equal in both directions, yet even in this case 

 the tendency to arrange itself according to the laws which 

 regulate inert matter might operate too powerfully, were it 

 not diminished by the association in equal atomic weights 

 of the two phosphates, each of which possesses a polarity in 

 some degree differing from the other, and consequently to a 

 certain extent counteracts the disposition in the particles of 

 the other to assume a determinate arrangement. 



If there be any truth in these speculations, is it not also 

 conceivable, that the interposition of a mineral matter, like 

 fluor spar, whose particles crystallize in quite another manner, 

 that is in cubes, may cooperate on the same principle, in im- 

 parting that freedom of motion to the particles of the prevailing 

 constituent of bones, by which it is rendered more pliant to 

 the purposes of the animal economy, more obedient to the 

 laws of life, more ready in short to insinuate itself into the 

 pores, so as to form the coats of those delicate capillary canals 

 of which the osseous structure appears to consist ? 



XIX. On a Spathic Carbonate qf Iron. 

 By Mr. John Thomas Way*. 

 nPHE mineral which forms the subject of the present notice 

 "'• was put into my hands by Professor Graham. It would 

 seem that its appearance had caused it to be mistaken for zinc 

 blende, which indeed it somewhat resembles in its colour and 

 lustre. Upon examination however it was found to contain 

 no zinc, but to be essentially a carbonate of the protoxide of 

 iron with hydrated peroxide of iron. 



The mineral is massive, of a brownish-black colour, pretty 

 compact structure, and exhibiting, when broken, crystalline, 

 generally rhomboidal and curved facets of a somewhat pearly 

 lustre. It is not homogeneous, some portions of it, when 

 crushed in an agate mortar, giving a powder of a much whiter 

 colour than others ; none of it is magnetic. 



Its specific gravity is 3*747. 



This mineral yields nothing to water, but (with the ex- 

 ception of a mere trace of silica) is entirely soluble with effer- 

 vescence in acids. Nitric and sulphuric acids dissolve it in the 

 cold, but more readily with the assistance of heat. Hydro- 



* Communicated by the Chemical Society; having been read March 18, 

 1844. 

 Phil. Mag. S. 3. Vol. 25. No. 164-. Augiist 184.4-. K 



