96 ATOMIC WEIGHT DETERMINATIONS. 



PHOSPHORUS. 



The specific beat of this element, as well as the density 

 of phosphorus and its numerous volatile compounds in the 

 gaseous state, corresponds to an atomic weight slightly 

 above 31. {Gmelin-Kraut, I. c.) 



V. Rose; F. H. Wollaston : 35.1 {0 = 1Q). 



Wollaston adopted the analysis of Rose, who found that 

 phosphoric anhydride contained 63.28 per cent, oxygen and 

 46.72 per cent, phosphorus. [This relation gives the above 

 value.] {Phil Trans., 101^, 1814, 20.) 



J. J. Berzelius : 31.225 (0 = 16). 



Berzelius made experiments on the reduction of auric 

 chloride and of argentic sulphate by phosphorus. His re- 

 sults were 0.8115 P = 13.98 Ag; 0.829 P = 8.714 Au ; 

 0.754 P = 7.93 Au. [The first of these analyses is misprinted 

 in the original memoir (Gilbert's Ann., 53., 433).] In the 

 Lehrbuch it is miscalculated as Ruecker has shown. Ber- 

 zeUus preferred deducing the atomic weight of P from that 

 of silver, because the atomic weight of the latter was more 

 accurately known than that of gold. [If Ag = 107.93, the 

 data give P = 31.325, for Au = 196.67 the latter analyses 

 give P = 31.176 and 31.165.] In all the experiments the 

 precipitated metal was boiled with the solution when the 

 reduction was nearly complete. A trace of gold was 

 observed to precipitate after the experiments were over. 

 The silver was heated to redness before weighing. [J. P. 

 Cooke, Jr., has shown (atomic weight of antimony) that 

 silver is volatile at a red heat. Berzelius must therefore 

 have got too large a result.] The phosphorus was distilled, 

 melted in a glass tube and cooled very slowly, to permit 

 traces of oxides to rise to the surface, and the lower portion 

 of the tube with the phosphorus broken oft' and instantly 

 weighed. {Gilbert's Ann., 53, 1816, 433, and Lehrbuch 3, 

 1188.) 



J. Pelouze : 32.0U (0 = 16) ; 200.15 (O = 100). 



A known weight of argentic nitrate was brought in con- 

 tact with a known and slightly excessive weight of phos- 

 phorous chloride and the excess titrated. The number of 

 experiments is not given. Ag = 1349.01 ; CI = 443.2. 



