CARBOX. DUMAS. IO5 



We cannot get a general mean of all determinations 

 made for carbon, by including any determinations of Van 

 der Plaats, because he made none on purest carbon, the 

 diamond. 



It is perfectly in order to find all determinations made on 

 any sort of carbon treated as one, individually affected by 

 11 probable errors " only, in the chemical olla fodrida of 

 Clarke, furnished by the Smithsonian Institution of Wash- 

 ington. 



But it is too bad for a good English Chemist to apply a 

 minute correction to all such determinations indiscrimi- 

 nately and then give us a corrected atomic weight of carbon 

 to the fourth decimal place. 



This correction, applied to all sorts of carbon, and the 

 " corrected " result C = 12.0008 copied into Ostwald's Zeit- 

 schrift is really more than even my tolerant nature could 

 stand. 



May we not expect that the chemists of to-day will use a 

 modicum of common sense when handling the subject of 

 atomic weights? 



After a patient and careful consideration of all experi- 

 mental determinations made with the purest material and 

 by the most sensitive method of Dumas, I am convinced that 

 the atomic weight of true carbon does not differ by as much 

 as one thousandth of a unit from the exact number 12, the 

 atomic weight of oxygen being taken at 16 exactly. 



As a most characteristic chemical curiosity I translate 

 from page 85 of Ostwald's Physik. Chemie, Bd. I, 1891, the 

 following : 



" There can remain no doubt but the atomic weight of 

 tc carbon is to that of oxygen as 12 to 16, -within the errors of 

 tf the experiments, and which may amount to a few ten- 

 IC thousandths of the total value. We use the value 

 "C = 12.003." 



First declare it is 12 exactly, within the minute errors of 

 the experiment; then use a different value throughout the 

 work, thus known to be wrong. u Es muss auch solche 

 Kautee geben." 



