Intelligence and Miscellaneous Articles. 389 



in the manner described by him in 1847 *, be plunged into a solution 

 of nitrate of silver, it will disappear ; if the paper or glass be now 

 exposed to the light for a few seconds, the iodide of silver, into which 

 the iodide of amidone which formed the primitive design has been, 

 converted, being much more sensitive than the nitrate of silver with 

 which the rest of the surface is imbued, is acted upon much more 

 rapidly ; if the paper or glass be then dipped into a solution of gallic 

 acid, the design is immediately reproduced, and it is then treated 

 with hyposulphite exactly as is done with photographic pictures. 

 By this process the design becomes as permanent as these latter, 

 and it will probably be adopted in many cases. 



M. Bayard has just made another application of the vapour of 

 iodine ; after exposing the engraving to the vapour of iodine, he 

 applies it upon a glass prepared with sensitive albumen, so as to form 

 a negative picture, with which he then takes positive impressions on 

 paper in the usual manner. In this manner he has obtained beautiful 

 reproductions of very old engravings without any distortion of the 

 image. — Comptes Rendus, March 28, 1853, p. 581. 



REMARKS ON THE STRUCTURAL CONDITIONS OF IRON. 

 BY T. R. V. FUCHS. 



The difference in physical characters presented by the several 

 kinds of iron is generally attributed to the presence of a variety of 

 substances, among which carbon is considered the most important. 

 It is contained in all kinds of iron, almost always accompanied by 

 silicon, which perhaps exercises the same influence. Raw iron 

 contains the largest quantity of carbon, bar iron the least, and steel 

 is in some sort intermediate between the two ; but the quantity of 

 carbon does not in any case bear a constant proportion to the iron,, 

 nor are these three kinds of iron separated from each other by any 

 definite limits. These two facts are sufficient to show that the car- 

 bon cannot be in a state of very intimate combination with the iron, 

 and there are no sufficient grounds for assuming that the different 

 conditions of this metal are determined solely by the quantities of 

 carbon contained in it. The numerous, and in many respects valu- 

 able analyses of iron have served only to prove the truth of the 

 above remark. Upon the gratuitous assumption that the varying 

 per-centage of carbon is the cause of the differences in character 

 of iron, attention has been too exclusively devoted to this point, 

 while another, and perhaps more essential one, the crystalline struc- 

 ture, has been overlooked. 



Fuchs expresses his conviction that iron is a dimorphous substance, 

 that there are, in fact, two species (varieties) of iron, — the tesseral 

 and the rhombohedral. He considers it as proved that malleable 

 iron belongs to the tesseral system ; and if any doubt still exists, it 

 may be inferred from analogy that such is the case, inasmuch as all 

 other malleable metals possess crystalline forms belonging to this 

 system. 



The crystalline form of raw iron has not been ascertained with so* 

 much certainty, but Fuchs considers it highly probable that it be- 

 * See Phil. Mag. Ser. 3. vol. xxxii. p. 206. 



