PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 409 



Mr. Rowell stated that steel could not be burned in an alcohol 

 blaze ; it was impossible to spoil it. In burning a roll full of 

 hard spots, which the tools could not cut, tools Avere made and 

 hardened in quicksilver, which was successful. 

 • Mr. Dibben. — Steel should be tempered at the lowest tempera- 

 ture at which it can be made hard. 



Mr. Harrison mentioned the fact that the grain of hardened 

 steel is somewhat coarser than of that which is soft ; and that 

 steel expands in hardening. 



The Chairman stated that lead had been supposed to injure 

 steel ; and zinc had been found rather to improve it. 



Mr. Harrison. — I should suppose that the extreme volatility of 

 zinc would be an objection. 



Dr. Brower classified iron as follows : 



Red short. 



Cold short. 



( Pure neutral. 



„ , Manganese neutral. 



Neutral. < ^. , 



j Zinco-neutral. 



• ^^ Mang. zinco-neutral. 



The property of red-shortners, or being brittle when at a red 

 heat, is usually said to be derived from sulphur. The property of 

 cold-shortners, or being brittle when cold, is said to be derived from 

 phosphorus existing in phosphate of lime.* When manganese 

 and zinc are contained in a neutral iron, they have a tendency to 

 overcome the effects of sulphur and of phosphorus. By the man- 

 agement of the puddling furnace the decorbonization may be so 

 graduated that instead of a true fibrous iron a semi-steel is pro- 

 duced which has the appearance of cold short iron, and may be 

 converted into a good steel. A. great deal of steel is thus made 

 which might not be merchantable for ordinary use, but which is 

 at once made into sledge hammers, crowbars, and similar tools, 

 for Avhich it is adapted, and is thus readily brought into the 

 market. 



Mr. Tillman stated that according to the modern theory, car- 

 bon and nitrogen are both essential in the formation of steel, and 

 therefore substances containing cyanogen, as the cyanite of potas- 

 sium, are used in the hardening process. But Joseph Dixon, of 

 Jersey city, boldly takes the ground that neither carbon nor nitro- 



* Neither of these ideas appear to be sustained by facts. — J. R. 



