A HISTORY OF SCIENCE 



chemists among the leaders of their science who have 

 refused to admit that the so-called elements are really 

 elements at all in any final sense, and who have sought 

 eagerly for proof which might warrant their scepticism. 

 The first bit of evidence tending to support this view 

 was furnished by an English physician, Dr. William 

 Prout, who in 1815 called attention to a curious relation 

 to be observed between the atomic weight of the vari- 

 ous elements. Accepting the figures given by the au- 

 thorities of the time (notably Thomson and Berzelius), 

 it appeared that a strikingly large proportion of the 

 atomic weights were exact multiples of the weight of 

 hydrogen, and that others differed so slightly that er- 

 rors of observation might explain the discrepancy. 

 Prout felt that it could not be accidental, and he could 

 think of no tenable explanation, unless it be that the 

 atoms of the various alleged elements are made up of 

 different fixed numbers of hydrogen atoms. Could it 

 be that the one true element the one primal matter 

 is hydrogen, and that all other forms of matter are but 

 compounds of this original substance? 



Prout advanced this startling idea at first tentatively, 

 in an anonymous publication; but afterwards he es- 

 poused it openly and urged its tenability. Coming 

 just after Davy's dissociation of some supposed ele- 

 ments, the idea proved alluring, and for a time gained 

 such popularity that chemists were disposed to round 

 out the observed atomic weights of all elements into 

 whole numbers. But presently renewed determina- 

 tions of the atomic weights seemed to discountenance 

 this practice, and Prout's alleged law fell into disrepute. 

 It was revived, however, about 1840, by Dumas, whose 



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