154 Mr H. Meikle's Refutation of Mr Ivory's New Law of 

 and the new law announced above is 



« 8 ^ 



Two very different laws to be sure. If t z=: 32° F., and con- 

 sequently a = -77^ for Fahrenheit's scale, we have, 



For 1825, i = 480° (?^ — l). 



For 1827, i = 180° x ^-^=^. 



The truth of all I have alleged against the new law will now 

 be manifest ; particularly, that the quantity i can never amount 

 to 180° ; that is, the temperature can never, by condensation, 

 be raised 180°, or to the boiling point of water. So that, un- 

 der the new law, we need never attempt to kindle tinder in a 

 condensing syringe. 



If we compute the increase of temperature foi* a quadruple 

 condensation, by means of the formula given in 1825, viy. 



we shall find, that the rise of temperature on the common scale, 

 or the value of /, obtained by putting § = 4, is exactly equal to 

 the sum of the rises obtained at two operations, taking an inter- 

 mediate density. Thus, put § = 2, and find the value of i ; 

 then add this to r, and find a second value to i; it M^ill be 

 found, that the whole rise of temperature is precisely the same 

 in both ways. The character of the formula, therefore, re- 

 mains unsullied by this test, though I do not mean to say that 

 this is a complete and positive proof of its correctness. On first 

 seeing that formula in M. Poisson's memoir, I tried it by this 

 test, and the result did not lower its value in my estimation. 



It is plain, that any formula which will not bear to be so 

 handled, must be a mere visionary shadow, self-condemned, and 

 good for nothing. I therefore proceed to apply the same 

 simple test to the trial of the new law. 



The new law of condensation is, of course, meant to be quite 

 general in its application, — answering alike for all moderate 



