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Heat capacity of metals and metallic compounds
360
J.A.P.
CHSSIELD.
master the work in a gas plant, that some gas companies have entirely restricted additions to their engineering forces to this class. When we consider the immense amount of intelligent work which has been expended upon the engineering problems in a gas works, it is not to be expected that any very great economies in manufacture will be made. What reductions in the cost of the finished product will be made wit1 be accomplished by close attention to the small savings possible in increasing thermal and mechanical efficiencies and in the substitution of mechanical appliances for human labor. These are problems which will be solved only by the trained mechanical engineer.
Heat Capacity of Metals and Metallic Compounds. H. SCHI~PFr. (Zeit. Phys. Chem., lxxi, 257,)--The heat capacities of 15 pure metals and 29 metal compounds have been determined by the method of mixtures in the three temperature intervals Iy°C. to Ioo°C., Iy°C. to --79°C. and I7°C. to --I9o°C., and the results agree very closely with the calculated values of the specific heats. Between @5o°C. a n d - - I s o ° C , the temperature coefficient of specific heat decreases with rising temperature for both metals and the inter-metallic compounds, except in the cases of lead and bismuth. In general the difference between the observed and calculated values of the specific heats of the inter~metallic compounds lies within 4 per cent. The observed specific heats of magnesium alloys are lower, and those of antimony alloys are higher than the calculated values. The atomic heats of metals and metallic corripounds increase with increasing temperature. Tar Roads. (E,ag. Rec., lxii, 7-) In ~9o9 the Massachusetts State Highway Commission used English spraying machines to apply tar coatings to road surfaces. The tar is heated by a coil supplied with steam from a traction engine. The tar is kept under pressure by pumps geared to the wheels of the truck so that the motion of the tar spraying machine develops the necessary pressure. The hot tar is spread through a number of small nipples which throw a fine spray, and spread it upon the road in a thin and even coat. A hood over the nipples prevents the tar from being blown to one side by the wind. When a heavy grade of oil is used and applied hot at the rate of half a gallon per square yard the cost is said to vary beteen 6 and II cents per square yard, including material, labor, and the surface covering of sand. gravel, or stonescreenings.
J.A.P.
CHSSIELD.
master the work in a gas plant, that some gas companies have entirely restricted additions to their engineering forces to this class. When we consider the immense amount of intelligent work which has been expended upon the engineering problems in a gas works, it is not to be expected that any very great economies in manufacture will be made. What reductions in the cost of the finished product will be made wit1 be accomplished by close attention to the small savings possible in increasing thermal and mechanical efficiencies and in the substitution of mechanical appliances for human labor. These are problems which will be solved only by the trained mechanical engineer.
Heat Capacity of Metals and Metallic Compounds. H. SCHI~PFr. (Zeit. Phys. Chem., lxxi, 257,)--The heat capacities of 15 pure metals and 29 metal compounds have been determined by the method of mixtures in the three temperature intervals Iy°C. to Ioo°C., Iy°C. to --79°C. and I7°C. to --I9o°C., and the results agree very closely with the calculated values of the specific heats. Between @5o°C. a n d - - I s o ° C , the temperature coefficient of specific heat decreases with rising temperature for both metals and the inter-metallic compounds, except in the cases of lead and bismuth. In general the difference between the observed and calculated values of the specific heats of the inter~metallic compounds lies within 4 per cent. The observed specific heats of magnesium alloys are lower, and those of antimony alloys are higher than the calculated values. The atomic heats of metals and metallic corripounds increase with increasing temperature. Tar Roads. (E,ag. Rec., lxii, 7-) In ~9o9 the Massachusetts State Highway Commission used English spraying machines to apply tar coatings to road surfaces. The tar is heated by a coil supplied with steam from a traction engine. The tar is kept under pressure by pumps geared to the wheels of the truck so that the motion of the tar spraying machine develops the necessary pressure. The hot tar is spread through a number of small nipples which throw a fine spray, and spread it upon the road in a thin and even coat. A hood over the nipples prevents the tar from being blown to one side by the wind. When a heavy grade of oil is used and applied hot at the rate of half a gallon per square yard the cost is said to vary beteen 6 and II cents per square yard, including material, labor, and the surface covering of sand. gravel, or stonescreenings.