THE YOUNG FARMER'S MANUAL. 373 



of hardness. If the cutting edge of the tool were formed in that 

 part which presented a greyish-white color, it would be so hard 

 that it would not retain a cutting edge, either for cutting iron or 

 wood. Now if this hard or grey portion of the tool were ground 

 off until the cutting edge is formed in that part which was of a 

 straw color, the cutting edge would usually be hard and tough, 

 suitable for cutting iron. Now grind off all the straw-colored 

 portion, so that the cutting edge will be in the sky-llue part, and 

 in good steel we would have an edge most suitable for cutting 

 wood. Now the idea always is, if we know about how hard it is 

 desired to have the steel of which tools are made, we have only 

 to heat the whole tool to such a degree of heat and plunge it 

 into cold water, when the entire steel will possess a given degree 

 of hardness. Sometimes one kind of steel must necessarily be 

 made a little harder than another kind, for the same purpose ; and 

 sometimes the steel of which a tool is made is of such an inferior 

 q^felity that it is impossible to give it such a temper as will retain 

 a good cutting edge. Tools are sometimes heated to redness, and 

 plunged into cold water and partially cooled, and then heated in 

 the fire until they exhibit the desired color, when they are 

 plunged into the water and cooled. Large tools, such as saws, 

 scythes, &c., are heated in large ovens to a given degree of heat, 

 when they are slipped instantaneously into a large tank of oil or 

 water to cool them. 



534. Different steel requires different degrees of heat. Now, 

 when the young farmer has an axe jumped, or a pick repaired, he 

 should tell the workman to remember and note the cdlor or degree 

 of heat at which the edge was tempered, and if the edge upon 

 trial proves to be too hard or too soft, if he is a skillful work 

 man he will be able the second time to temper the edge of the 

 desired hardness and toughness. I find that almost all kinds of edge 

 tools as the cutting edge is worn off become softer, and will not 

 retain an edge well. I heat such tools in a charcoal not mineral 

 coal fire to redness ; and cool about two inches of the cutting 

 edge, and then if it is desired to have a cold-chisel edge, cool it 

 just as the straw-color begins to appear at the edge. If for cut- 



