82 THE ATOMIC WEIGHTS. 



PHOSPHORUS. 



The material from which we are to calculate the atomic 

 weight of phosphorus is by no means abundant. Berzelius, 

 in his Lehrbuch,* adduces only his own experiments upon 

 the precipitation of gold by phosphorus, and ignores all the 

 earlier work relating to the composition of the phosphates. 

 These experiments we will consider with reference to gold. 



Pelouze,t in a single titration of phosphorus trichloride 

 with a standard solution of silver, obtained a wholly erro- 

 neous result ; and Jacquelain,| in his similar experiments, 

 did even worse. Schrotter's criticism upon Jacquelain suf- 

 ficiently disposes of the latter.|| 



There are, in short, but two investigations upon the 

 atomic weight of phosphorus which have any value for 

 present purposes, namely, the researches of Schrotter and of 

 Dumas. These chemists worked with different materials 

 and by different methods, and yet obtained beautifully con- 

 cordant results. 



Schrotter§ burned pure amorphous phosphorus in dry 

 oxygen, and weighed the pentoxide thus formed. One 

 gramme of P yielded P.^Or, in the following proportions : 



2.28909 



2.287S3 



2.29300 



2.2S831 



2.29040 



2.2S788 



2.28848 



2.28856 



2.28959 



2.28872 



Mean, 2.289186, ± .00033 



Hence P = 30.9562, ± .0074. 



*5th Ed., 1 1 88. 



f Compt. Rend., 20. 1047. 



X Compt. Rend., ^2i- ^93- 



ll Journ. fiir Prakt. Chem., 57, 315. 



g Journ. fur Prakt. Chem., 53, 435. 1S51. 



