THOSrHORUS. 209 



PHOSPHORUS. 



The material from which we are to calcuhxte the atomic weiglit 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 have been considered with refer- 

 ence to gold. 



Pelouze,t in a single titration of phosphorus tricliloride with a stand- 

 ard solution of silver, obtained a wholly erroneous result ; and Jacque- 

 lain,;}: in his similar experiments, did even worse. Schrotter's criticism 

 upon Jacquelain sufficiently^ disposes of the latter. § 



Only the determinations made by Schrotter, Dumas, and Van der 

 Plaats remain to be considered. 



Schrotter II burned pure amorphous phos[)horus in dry oxygen, and 

 weighed the pentoxide thus formed. One gramme of P yielded 1^0^ in 



the following proportions : 



2.28909 

 2.28783 

 2.29300 

 2.28831 

 2.29040 

 2.28788 

 2.28848 

 2.28856 

 2.28959 

 2.28872 



Mean, 2.289186, ± .00033 



Dumas ^ prepared pure phosphorus trichloride by the action of dry 

 chlorine upon red phosphorus. The portion used in his experiments 

 boiled between 76° and 78°. This was titrated with a standard solution 

 of silver in the usual manner. Dumas publishes weights, from which I 

 calculate the figures given in the third column, representing the quantity 

 of trichloride proportional to 100 parts of silver : 



1.787 grm. PCI3 ^ 4.208 grm. Ag. 42.4667 

 1.466 " 3.454 " 42.4435 



42.4443 

 42.4528 

 42.4690 



Mean, 42-4553, ± .0036 



14 



*5th ed., 118S. 

 tConipt. Rend., 20, 1047. 



I Compt. Rend., 33, 693. 



^ Journ. fiir Prakt. Cheni., 57, 315. 



II Journ. fiir Prakt. Chera., 53, 435. 1851. 

 II Ann. Chein. Pharm., 113, 29. 1S60. 



