1903.] Specific Heats, especially al Low Temperatures. 185 



72 grammes, calorimeter E, fall of temperature approximately 3'5. 

 In the second set of experiments the amount of liquid air entering the 

 calorimeter was distinctly less than in the first ; the inference, there- 

 fore, that may be drawn from the approximate identity of the results 

 in the two sets of experiments is that in neither case was the amount 

 of liquid air calorimetrically of much consequence. 



A commercial casting gave, after a rough trimming in the lathe 

 0'153 (3), 0-154 (3), and, after a final shaping and smoothing, 0*153 (3), 

 0*1525 (3). Mass (in the second pair of experiments) approximately 

 88 grammes. An analysis by Mr. Race showed aluminium 88 per cent., 

 zinc 7 per cent., copper 4 per cent., the balance lead, iron, silica, etc., 

 with a trace of nickel. The specific heat found is much lower than 

 would be indicated by this analysis and Regnault's law of mixtures. 



Iron. 



A ball of cast-iron, mass approximately 110J grammes, gave in two 

 experiments 0'0897 (3), 0-0889 (5). These experiments were made 

 merely for comparison with the results given by the ice method described 

 later. 



Nickel 



A specimen supplied by Johnson, Matthey and Co., was found by 

 Mr. Race to contain nickel and cobalt 98*5 per cent, (cobalt approxi- 

 mately 0*9 per cent.), iron 0*6 per cent., copper 0'7 per cent., some 

 silica. It gave 0-0848 (5), 0'0842 (5), 0'0840 (5), mean 0-0843. Mass 

 approximately 192 grammes, calorimeter E, fall of temperature 

 approximately 4"5. 



Cobalt. 



A specimen supplied by Johnson, Matthey and Co., was found 

 by Mr. Race to contain cobalt and nickel 97*5 per cent, (nickel 

 0-5 per cent, approximately), iron 1*9 per cent., small quantities of 

 copper, lead, carbon and a trace of zinc. It gave 0"0843 (5), 0-0846 (5), 

 0-0841 (5), mean 0*0843. Mass approximately 165 grammes, calorimeter 

 E, fall of temperature approximately 3 "9. 



Zinc. 



A specimen of Dr. Mond's metal, supplied by Johnson, Matthey, 

 and Co., gave 0*0838 (3), 0*0839 (4), 0-0840 (5), mean 0-0839. Mass 

 approximately 169 grammes, calorimeter E, fall of temperature approxi- 

 mately 4*0. 



A second specimen, nominally pure, gave 0-0849 (5), 0*0854 (5). Mass 

 approximately 71 grammes. In this specimen Mr. Race found 99*7 

 per cent, zinc, no trace of any other metal. 



