September 6, 1907] 



SCIENCE 



303 



quantitative chemistry, we find, upon com- 

 paring the probable accuracy of most re- 

 sults in chemistry with the probable ac- 

 curacy of many results in physics and 

 astronomy, that chemistry is at present far 

 in the background. In physics or as- 

 tronomy results attaining an accuracy of 

 one part in a hundred thousand are by no 

 means uncommon, and often a much higher 

 degree of precision than this is reached. 

 For example, in weighing it is easy to 

 detect one tenth of a milligram in a kilo- 

 gram, a fractional part of only one in ten 

 million. Again, the length of the year in 

 terms of the length of the mean solar day 

 is probably known to within one part in a 

 hvindred million. On the other hand, in 

 chemistry few results are to be relied upon 

 to within one part in 500, and many 

 investigations, even of the atomic weights, 

 have yielded results which are not to be 

 trusted within one per cent. Such an 

 error is 100,000 times as great as the pos- 

 sible error of the process of weighing alone. 



Why is chemistry still so much behind 

 physics and astronomy in quantitative con- 

 sistency, when all three sciences depend 

 upon the same methods of measurement? 

 Are the supposed constant magnitudes to 

 be measured in chemistry really variable, 

 that their range of uncertainty should be 

 so large? If they are thus variable, is it 

 worth while to expend much labor in de- 

 termining the values which they happen to 

 possess at any one time under any one 

 set of conditions? 



The question as to whether or not the 

 supposed constants of physical chemistry 

 are really not constants, but are variable 

 within small limits, is of profound interest 

 and of vital importance to the science of 

 chemistry and to natural philosophy in 

 general. If this latter alternative is true, 

 the circumstances accompanying each pos- 

 sible variation must be determined with the 



utmost precision in order to detect the 

 ultimate reason for its existence. As Dem- 

 ocritus said long ago, ' ' the word chance is 

 only an expression of human ignorance." 

 No student of natural science who perceives 

 the dominance of law in the physical uni- 

 verse would be willing to believe that such 

 variation in a fundamental number could 

 be purely accidental. Every variation 

 must have a cause, and that cause must be 

 one of profotind effect throughout the 

 physical universe. Thus the idea that the 

 supposed constants may possibly be vari- 

 able instead of invariable, adds to the in- 

 terest which one may reasonably take in 

 their accurate determination, and enlarges 

 the possible field of investigation instead 

 of contracting it. 



Possible variability is by no means the 

 only reason for being interested in the more 

 accurate determination of the physico- 

 chemical contents, however. Many con- 

 siderations show that whether the con- 

 stants are changeable or not, more time 

 and care may be profitably spent upon 

 them than has been spent in the past. The 

 argument may be epitomized by referring 

 back to the theorem of Plato, and some- 

 what extending it. Plato said : when meas- 

 uring and weighing and mathematics are 

 taken from an art, there is little left of 

 that art. May we not add that the more 

 efficiently weighing and measuring are used 

 in any art, the more valuable that art be- 

 comes? If, as Kant has it, a subject be- 

 comes truly scientific only when its facts 

 are susceptible of mathematical treatment, 

 then an extrapolation enables us to say 

 that a subject becomes the more scientific 

 the more accurately the mathematical 

 premises are ascertained. Huxley was 

 wont to say that mathematics might be 

 compared to a mill which would grind 

 exceedingly fine all that was placed within 

 it, but was incapable of making wheat 



