242 Dr, Thomson's Experiments to determine the Weight [April, 



of the metals, whose names are affixed to the title of this essay, 

 and has enabled me to determine their atomic weights with equal 

 precision ; but with mercury, bismuth, and tin, some modifica- 

 tions will be requisite. The difficulty with respect to mercury 

 is to obtain its nitrate perfectly free from water. The chlorides 

 of tin and of bismuth are easily procured in a state of dryness ; 

 but when thus freed from water, I could neither dissolve them 

 completely in nitric acid, acetic acid, or water ; and the addition 

 of muriatic acid destroys the precision of the process. 



My object at present is to relate the experiments which I have 

 made to determine the weights of the atoms of the six metals 

 whose names are enumerated in the title to this essay. The 

 following table exhibits the atomic weights of these bodies 

 according to the best experiments hitherto published. 



Dalton.* 



Copper 7-0 



Zinc 7-0 



Iron 6-25 



Manganese 5 ? 



3Nrickel....|3-125?or6-25? 

 Cobalt.... 6-875? 



Thomson. 



8-0 



4-25 



3-5 



3-5 



3-25 



3-25 



The numbers given by Berzelius being alone (except my own), 

 deduced from original experiments, it will be worth while to 

 compare them with mine ; but to fit them for that comparison, 

 it will be requisite to divide all of them, except the first, by 2. 

 This gives us their weights as follows : 



Copper 7-91390 



Zinc 4-03225 



Iron 3-39215 



Manganese 3*55785 



Nickel 3-69755 



Cobalt 3-69000 



The long train of decimals attending almost every one of these 

 numbers is sufficient of itself to render their accuracy suspicious. 

 Nature is not wont to indulge in such complicated relations. 

 Indeed the very simple numbers, which we have already obtained 

 for the atomic weights of the 14 bodies formerly examined, lead 

 almost irresistibly to the conclusion that the same simplicity will 

 be found to pervade the weights of all the simple bodies in 

 nature. We shall see immediately at least that the law holds 



• New Syitem of Chemistry, p. 546. I have divided his number by 8, 

 + Phil. Trans. 1814, p. 18. 



X Essai sur la Theorie des Proportions Chimiques. I'able at the end. 

 § Annalt of Philosophy^ vi. 329. Most of his numbers are deduced from Berzelius** 

 experiments. 



