IS14.] Chemical Proportions. S7 



Weight of an 

 atom. 



Cobalt 7*326 * 



Manganese 7'1 15 * 



Molybdenum 6-013 a 



Tungsten 12-121 b 



Cerium 11-487 c 



2S/ Chromium 4-720 d 



arsenic [Annals of Philosophy, vol. iii. p. 93); but I sliall insert a 

 short disquisition on tbe subject in the next number of this work. 



y I think it deserves to be noticed that the weights of an atom 

 of each of the three magnetic metals very nearly coincide. They 

 are as follows : — 



Iron 7-H3 



Nickel 7-305 



Cobalt 7-32G 



They agree likewise in the number and constitution of their 

 oxides, which are as follows : — 



Iron. Nickel. Cobalt. 



First oxide ....I i + 2 o ... A n + 2 o ... A c + 2 o 

 Second oxide ...1 i + 3o....l n + 3o....l c -t- 3o 



1 have no doubt that the composition of their carburets, phos- 

 phurets, and sulphurets, will likewise be found to agree. 



1 There was an arithmetical error in the original number in the 

 first table. 



a According to the experiments of Bucholz, modified a little by 

 the subsequent experiments of Berzelius described in the Annuls of 

 Philosophy, vol. iii. p. 100. 



b This results from the experiments of Berzelius, who found the 

 two oxides of tungsten composed respectively of 100 metal + 16-5 

 oxygen and 100 metal + 24*75 oxygen {Annals, vol. iii. p. 244). 

 The first oxide is brown, and burns spontaneously when exposed to 

 the air. It was obtained by passing a current of hydrogen gas 

 through red-hot tungstic acid. The second is tungstic acid. Ber- 

 zelius has shown that the blue oxide of Bucholz is the same with 

 tungstic acid. It is obvious that the numbers 16-5 and 24-75 are to 

 each other as 2 -. 3. 



The data are the same as those I used before ; but there is a 

 ■light arithmetical error in the number given in my first table. 



d Berzelius has shown that there are three oxides of chromium 

 {Annuls of Philosophy, vol. iii. p. 101), the green, the brown, and 

 the acid. The first contains 100 metal + 42-157 oxygen, while the 

 acid is composed of 100 metal + 81-74 oxygen. These numbers 



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