Intelligence and Miscellaneous Articles. 399 



If, on the other hand, we make c=0° C, whilst a, b, i" and <* 

 remain unaltered, we find 1'-'= — 79'39* ; this last number is there- 

 fore the lowest limit of evaporation of water. 



The formula (1) may therefore be converted into the following : — 



t + id - ^b ^ ^ 



The temperatures (counted from the lowest limit of evaporation) 

 are consequently related as the sixth roots of the pressures, or the 

 pressures stand in the proportion of the sixth powers of the tem- 

 peratures. 



In 1849 I found the formula 



273 + 100 _ 273 + T .3. 



273 + e ~"273 + r ^ ' 



which expresses that, if all temperatures be counted from — 273° C, 

 all the corresponding temperatures for any two fluids are propor- 

 tional. 



(100 is the boiling-point of water or of any fluid; T and t are two 

 corresponding temperatures of water and the other fluid.) 



This formula I have been able to verify from the experiments of 

 Regnault and Faraday, for alcohol, carbonic acid, and nitrous acid 

 gas ; other fluids, such as aether, but especially sulphuret of carbon, 

 exhibit considerable differences in opposition to the formula; I shall 

 hereafter publish the results of my calculations upon them. 



If we assume that the formulae (3), (1), and (2) are in general 

 applicable to all fluids, and indicate by <° the lowest limit of evapo- 

 ration of a fluid boiling at e, this limit may be calculated by the 

 formula 



i°=-273 + -^Z^±^ (273-79) (4) 



273 + 100^ ^ 



The formulae (1) and (2) then become 



ta-e^a ^'-im^ (5) 



t''-e li-iQQx 

 and 



^-;i:i:=4. (6) 



Z*-i° lis 



Poggendorff's Annalen, 1858, No. S. p. 651. 



ON INTERMITTENT FLUORESCENCE. BY J. MlJLLER. 



In a strij) of paper which was washed over with a solution of 

 platinocyanide of barium, so that after the evaporation of the 

 water the paper was covered with a layer of delicate greenish cry- 

 stals, I observed the following singular pha^nomenon, which I may 

 cliaructcrizc as intermittent fluorescence. The spectrum produced 

 in a dark room by a flint-glass prism was projected by means of a 



* Of course somewhat diirereut Viilucs arc found if a and b be altercil ; 

 for a=2iP and i=0, we iuul —79-92; but we also Ihid numbers such as 



