8S DE. GOODMAN ON LIGHT, HEAT, 



a corroboration ; and my friend Mr. Joule has shown, that 

 considerably more heat is given off during the combustion 

 of a few grains of potassium, in oxygen gas, than by a like 

 quantity of any of the other metals, zinc, iron, &c., and 

 that the quantity given off by each metal, is in harmony 

 and proportion with their electrical powers in voltaic 

 arrangements. 



Experiment 1. — I found that when potassium is thrown 

 into a red hot crucible, it explodes, and produces a small 

 flash and sound, much resembling the deflagration of the 

 priming of a gun. Held in the flame of common gas, it 

 burns still more vividly, and throws off bright scintillations 

 like iron wire in oxygen gas. 



Ewp, 2. — When placed in a tube of metal or of glass, 

 hermetically sealed and submitted to the operation of the 

 blowpipe, at a given temperature it begins to force its way 

 out in vapour, and burns at the orifice, like charcoal and 

 nitrate of potash, with a hissing noise. 



ABSOLUTE HEAT. 



Attempts have frequently been made by philosophers 

 to find out the absolute caloric contained in different sub- 

 stances. It scarce need be added, that the intricacy of such 

 a subject has rendered great discrepancy in their results, 

 and shown their utter inability ever to grapple with it. 



But although it does not appear to appertain to man to 

 ascertiiin the absolute quantities, volume, weight, form, and 

 distance of the forces and nature of fiirst principles or ele- 

 ments, yet relative properties and quantities are to a great 

 extent within the grasp of philoso})hical research. 



COMPEESSION OF POTASSIUM. 

 Exp, 3. — The metal was now subjected to compression, in 

 order to exhibit the heat given off during the period in 

 which the elementary particles are supposed to be forced 



