OXYGEN. lo 



The results of the two series, reduced to a vacuum and stated as ratios, 

 are as follows : 



First. Second. 



Weight of H Weight of O 



Weight ot Al' Weight of Al 



o. 11180 0.8S788 



0.1 1 175 0.8S799 



0.1 1 194 0.S8774 



0.1 1 205 0.88779 



o.iriSg 0.8S785 



0.1 1 200 0.88.789 



0.11194 C.SS798 



o. II 175 o 8S7S7 



0.1 1 190 0.8S773 



o. 111S2 0.S879S 



0.1 1204 0.88785 



o. 11202 



O.I 1 204 0.88787,^0.000018 



O.III79 



O.I II 78 , 



O.I 1202 



O.I 1 188 



o. 111S6 



o. II 185 



o. II 190 



o. 1 1 187 



0.III90, ±0.000015 



Dividing the mean of the second column by the mean of the first, we 

 have for the equivalent of oxygen : 



088787,-1-0.000018 ^ , 



' ' ' -^ = 7-9345, ± o.ooii 



0.11190,^0.000015 



Hence = 15.8690, ± 0.0022. 



The details of the investigation are somewhat complicated, and involve 

 various corrections which need not be considered here. The result as 

 stated includes all corrections and is evidently good. The ratios, how- 

 ever, cannot be reversed and used for measuring the atomic weight of 

 aluminum, because the metal employed was not absolutely pure. 



We have now before us, representing syntheses of water, thirteen series, 

 as follows : 



Dulong and Berzelius O ^ 15.894, ± .057 



Dumas 15.9607, d= .0070 



Erdmann and Marchand 15-975, ± -O' '3 



Thomsen, 1870 I5-9I, ±-0113 



Cooke and Richard.s 15.869, ± .0020 



Keiser, 1887 15.864, dz .015 



" 1SS8 15.9514,^.0011 



