COPPER, SILVER, AND GOLD 439 



synthesis of silver bromide with the analysis of silver bromate gave the 

 figure 107-921. The synthesis of silver chloride and the analysis of 

 silver chlorate gave a mean result of 107-937. Hence there is no 

 doubt that the combining weight of silver is at least as much as 107*9 

 greater than 107-90 and less than 107-95, and probably equal to the 

 mean= 107-92. Stas determined the combining weights of many other 

 elements in this manner, such as lithium, potassium, sodium, bromine, 

 chlorine, iodine, and also nitrogen, for the determination of the 

 amount of silver nitrate obtained from a given amount of silver 

 gives directly the combining weight of nitrogen. Taking that 

 of oxygen as 16, he obtained the following combining weights 

 for these elements : nitrogen 14-04, silver 107 '93, chlorine 35-46, 

 bromine 79-95, iodine 126-85, lithium 7*02, sodium 23-04, potassium 

 39*15. These figures differ slightly from those which are usually 

 employed in chemical investigations. They must be regarded as the 

 result of. the best observations, whilst the figures usually used in 

 practical chemistry are only approximate are, so to speak, round 

 numbers for the atomic weights which differ so little from the exact 

 figures (for instance, for Ag 108 instead of 107-92, for Na 23 instead 

 of 23-04) that in ordinary determinations and calculations the 

 difference falls within the limits of experimental error inseparable from 

 such determinations. 



The exhaustive investigations conducted by Stas on the atomic 

 weights of the above-named elements have great significance in 

 the solution of the problem as to whether the atomic weights of the 

 elements can be expressed in whole numbers if the unit taken be the 

 atomic weight of hydrogen. Prout, at the beginning of this century, 

 stated that this was the case, and held that the atomic weights of the 

 elements are multiples pf the atomic weight of hydrogen. The subse- 

 quent determinations of Berzelius, Penny, Marchand, Marignac, Dumas, 

 and more especially of Stas, proved this conclusion to be untenable ; 

 since a whole series of elements proved to have fractional atomic 

 weightsfor example, chlorine, about 35-5. On account of this, 

 Marignac and Dumas stated that the atomic weights of the elements 

 are expressed in relation to hydrogen, either by whole numbers 

 or by numbers with simple fractions of the magnitudes ^ and J. But 

 Stas's researches refute this supposition also. Even between the com- 

 bining weight of hydrogen and oxygen, there is not, so far as is yet 

 known, that simple relation which is required by Front's hypothesis^ 



37 This hypothesis, for the establishment or refutation of which so many researches 

 have been made, is exceedingly important, and fully deserves the attention which has 

 been given to it. Indeed, if it appeared that the atomic weights of all the elements could 

 *H 



