Wrought Iron when Heated and then Cooled. 

 Fig. 12. 



397 



W.Xr, 



One-fourth of full size. 



Experiment 9. — A solid cast-steel cylinder, of the same dimensions 

 as that used in Experiment 5, was heated and cooled by half-immer« 

 sion twenty times. 



The effect obtained was similar to that produced upon the solid 

 wrought-iron cylinders, but the breaking up of the structure was dif- 

 ferent (see fig. 13). The greatest contraction was slightly above the 

 water-line, and amounted to *38 inch ; the bulgings on the ends were 

 •075 inch, being much less than on the wrought-iron cylinders. 



Experiment 10. — A hollow brass cylinder, 6 inches long, 2 inches 

 in diameter, and y^th of an inch thick, was heated to redness and 

 cooled by half-immersion thirty-four times. 



The effect produced was the opposite to that which took place with 

 the iron cylinders, being an expansion instead of a contraction at the 

 water-line, the amount of which was * 1 75 inch, and it was also ex- 

 panded on the lower edge '1 inch (see fig. 16). 



Experiment 1 1 . — A hollow gun-metal cylinder was heated to red- 

 ness and cooled twenty times by half-immersion. 



The thickness of metal being greater than in the last experiment, 

 the effect at the water-line was much less, but the lower edge had 

 expanded * 1 inch. It began to crack all over at the last cooling. 



Experiment 12. — A hollow tin cylinder was heated in linseed-oil 

 which was brought to a temperature of 400° Fahr. ; it was cooled by 

 half-immersion in water five times. 



The form was not altered in the least, though the heat was raised 

 in the last instance to the melting-point, as shown by the lower part 

 of the cylinder beginning to melt. 



Experiment 13. — A hollow zinc cylinder was heated and cooled by 

 half-immersion fifty times. 



It was heated in a wood furnace, the degree of heat to which it 



was found each time to have increased in weight up to the tenth heating, at which 

 point it weighed 50 lbs. 1*125 oz., or 2*625 ozs. heavier than it was at the com- 

 mencement ; from the tenth to the fifteenth he'ating the accumulated scales peeled 

 off, and the weight was gradually reduced to that stated above. 



That which was cooled in water weighed 50 lbs. 12*5 ozs. before the experiment, 

 and 48 lbs. 14*5 ozs. at its conclusion, giving a loss of 1 lb. 14 ozs., which was 

 due to the action of the water peeling off the scale each time the cylinder was 

 cooled. 



