1891.] Heat produced by compressing Liquids and Solids. 131 



Eise of temp, per ton. 



Vulcanite 030 



Glass 0-12 



Cork 0-75 



Beeswax , 083 



Chloroform 1'44 



Ether 1'80 



Paraffin (solid) 0*61 



Paraffin oil T39 



Owing to the unfortunate choice of substances, these results, 

 although of interest as illustrating the application of the method, can 

 have little, if any, general significance. In the year 1888 Mr. Burton 

 performed a similar series of experiments, with the view of gaining 

 some light on the physical constitution of allotropic forms of elemen- 

 tary substances. As the results have not hitherto been published, 

 they are here shortly recorded. The following table gives a resume 

 of the results obtained with the two forms of phosphorus and with 

 several metals. The method was in nearly all particulars the same 

 as that of Messrs. Creelman and Crocket. The powdered substances 

 were strongly compressed in short glass tabes, and the sharp-pointed 

 nickel-iron junction pressed into the powder. The metals were made 

 into little cylinders, and a hole drilled in each, very little larger than 

 the junction. The sample was fixed on the wires and then finely 

 powdered metal packed in, so as to leave the least possible air space. 

 This method proved fairly satisfactory for such metals as could be 

 obtained in ingots, and for very heavy and coherent powders, such as 

 graphite, arsenic, and amorphous phosphorus ; but it was, of course, 

 inapplicable to liquids, except water, and almost equally so to light 

 powders, like charcoal. 



The figures in column 2, showing the amount of heat produced by 

 a uniform pressure of about 300 atmospheres, or 2 tons, on the square 

 inch, seemed to indicate that in metals the heat produced by compres- 

 sion varied inversely as the atomic weight. The difference in the 

 heat given out by the two kinds of phosphorus is remarkable, and 

 may possibly be held to indicate a wide difference in molecular 

 weight. 



The results were not sufficient, either in number or accuracy, to 

 warrant the statement of any such law as that above mentioned, but 

 they were of quite sufficient interest to induce us to take up the 

 subject once more, using a larger number of substances and more 

 accurate methods. 



K '2 



