Manchester Memoirs, Vol. Iv. (191 1), No. 34. 3 



A second analysis was now taken of the steel at a 

 point about i inch from the cavity. It was not possible 

 to get clean drillings from any point further away from 

 the "pine-tree" crystal area than this owing to the metal 

 having been all machined away close to the cavity. 



Analysis outside of the " Pine- Tree " Crystal area. 



Combined Carbon ... ... ... -345 % 



Silicon ... ... ... ... -16 „ 



Manganese ... ... ... ... 102,, 



Sulphur ... ... ... ... -08 ,, 



Phosphorus ... 

 I have not the composi 



•076,, 



ition of the charge from which 

 the propeller-boss casting was made, but am informed 

 that the bulk of the metal in that particular casting 

 would not contain more than "05 to '06 of either sulphur 

 or phosphorus. There has, therefore, been considerable 

 segregation in the area where the " pine-tree " crystal 

 growth has occurred. 



A description of the external form of these " pine-tree " 

 crystals is not an easy matter. The " pine-tree " crystal 

 form was not produced in the laboratory work of 

 Dr. J. E. Stead and Messrs. Osmond and Cartaud, 

 although the individual component forms were. As early 

 pointed out by Tschernofif, Sorby, Andrews and others, the 

 crystal form of iron is regular. 



Osmond says that the crystal belonging to Professor 

 Tschernoff resembles a crystal of alum. This description 

 applies equally to those under consideration. Osmond 

 refers to the crystalline structures which characterise iron 

 in industrial products as resembling skeletons of octa- 

 hedrons united along the axis. He further refers to 

 some crystallites of the cubic system obtained from a 

 solution of chrome alum with orthogonal branches and 



