58 2 Notices respecting New Books, 



To effect this, a higher temperature and a more powerful 

 affinity must be exerted. That this effect is complete we 

 have no proof, but that a larger portion of metal is called 

 into existence. If the affinity continues to increase in the 

 ratio of the diminution of the quantity, then a much higher 

 temperature and a more powerful affinity may be requisite 

 to remove from iron the last portions of oxygen than any 

 with which we are acquainted. 



The external characters assumec} by iron separated in this 

 s hnple mode of assaying, are of much importance in under- 

 standing thoroughly the process. As long as malleable iron 

 continues to be precipitated, the metal, if covered with glass, 

 possesses a surface of the highest polish. The colours are 

 frequently various, chiefly shades of blue and azure, some- 

 times black-watery inclining to rich deep brown. The 

 union of carbon, even in small quantities, under the same 

 pressure of glass, is immediately known by the fine crystal- 

 line form vyhi.ch begins to spread over the surface : some- 

 times the entire surface is thus elegantly marked. As the 

 quantity of carbon increases to form steel, the crystallization 

 assumes a radiated structure, convex upon the upper surface 

 and concave below. This form continues through all the 

 states of steel, but in approaching to crude irori the under 

 surface loses the concave and crystallization, and assumes 

 a smooth skin, sometimes marked with hollows equally 

 smooth. When the combination' of carbon is sufficient to 

 change the fracture of the metal from white to mottled or 

 gray, every trace of crystallization then vanishes, and a sur- 

 face comparatively rough,, but highly convex on, all sides, 

 succeeds. 



JCLVIII. Notices respecting New Books t 



JVjLr. Parkinson, of Hoxton, to whom chemists are in^ 

 debted for a very useful publication, the Chemical Pocket 

 Book, of which we have more than once had occasion to 

 speak, has just published the first volume of a new work,, 

 which will be found extremely interesting and useful to 

 geologists and mineralogists. It is entitled, An Examina- 

 tion of the mineralized Remains of the Vegetables and Ani- 

 vials of the AvJedilv.vlan World, generally termed extras 

 Tieous Fpssih* 4 to, 471 pages and an index. 



This volume, which contains the vegetable kingdom, is. 

 embellished and illustrated with a frontispiece and nine 



4 P^tes, 



