ERRORS OF WEIGHING. 4! 



this fact incidentally, when stating that the diamond burnt 

 surely did not contain hydrogen not enough to give one 

 single milligramme of water from the combustion of a 

 diamond weighing 1,500 milligrammes. 



As will readily be understood, this shows that a diamond 

 of 13,500 milligrammes cannot contain as much as one 

 milligramme of hydrogen. 



Considered with reference to the analytical balances now 

 in the laboratories, the balance used by Dumas in this great 

 research was but an inferior instrument. 



This shows once again, that the accuracy of the instru- 

 ment at hand counts for very little in the value of real 

 scientific work done. 



Indeed I am tempted to say, that the very fine balances 

 now in our laboratories, are one cause of the inferior work 

 done in these laboratories the last forty years. 



The Balance used by Berzelius. 



If now we turn further back in the history of this great 

 determination of the atomic weights of the elements to the 

 real founder of this work, Berzelius, we find that the balance 

 used by him during the first twenty years was much inferior 

 to the balance of Dumas of 1840. 



For we find, in the earliest data of Berzelius for lead, that 

 he ordinarily took ten grammes of lead and gave the weight 

 of the product to the centigramme only. 



Quite a number of the actual weighings of Berzelius are 

 given on pages 13 and 15 of our True Atomic Weights, 

 1894. He gives generally the centigramme only; at times 

 he states the half centigramme by entering 5 as third decimal. 



We are therefore certain, that Berzelius, about 1810, 

 weighed habitually to the centigramme only, while Dumas 

 at 1840 weighed to the milligramme. 



Our Fine Balances. 



As a matter of fact, the best work done to-day in our 

 chemical laboratories is not reliable below the tenth of a 

 milligramme. 



