

1889.] On the Composition of Water. 429 



The following are the details of the determination of February 2, 

 chosen at random : 



Before combustion ____ G 14 +H + O2906 = G n ____ pointer 20'05 

 After .... G 14 +H + 0-4006 = G u .... pointer 20-31 



Hydrogen taken = O'llOO 0'00005 = 010995 gram. 



Before combustion ---- G 13 + O = G u + 2'237 . . . pointer 20'00 

 After .... G 13 + O = G n + 1-357 ... pointer 19'3 



Oxygen taken = O'8800+O'OOOl = 0'8801 gram. 



At the close of operations the residue in the eudiometer was oxygen, 

 occupying 7'8 c.c. This was at a total pressure of 29'6 16'2 = 13'4 

 inches of mercury. Subtracting 0'4 inch for the pressure of the 

 water vapour, we get 13*0 as representing the oxygen pressure. The 

 temperature was about 12 C. Thus, taking the weight of a cub. 

 cent, of oxygen at C. and under a pressure of 76"0 cm. of 

 mercury to be 0' 00143 gram, we get as the weight of the residual 

 oxygen 



0-00143 _ *1 8 __ 33-0x2-54 . 0046 

 1 + 12x0-00367 7b'-0 



The weight of oxygen burnt was, therefore, 0'8801 0'0046 

 = 0-8755 gram. 

 Finally, for the ratio of atomic weights, 



= 15-926. 



, 



jt Hydrogen 



In several cases the residual gas was subjected to analysis. Thus, 

 after the determination of February 2, the volume was reduced by 

 additions of hydrogen to 1*2 c.c. On introduction of potash there 

 was shrinkage to about 0'9, and, on addition of pyrogallic acid, to 

 O'l or 0'2. These volumes of gas are here measured at a pressure of 

 I atmosphere, and are, therefore, to be divided by 3 if we wish to 

 estimate the quantities of gas under standard conditions. The final 

 residue of (say) 0'05 c.c. should be nitrogen, and, even if originally 

 mixed with the hydrogen the most unfavourable case would involve 

 an error of only -^Q-Q i n ^ ne final result. The O'l c.c. of carbonic 

 anhydride, if originally contained in the hydrogen, would be more 

 important ; but this is very improbable. If originally mixed with the 

 oxygen, or due to leakage through india-rubber into the combustion 

 apparatus, it would lead to no appreciable error. 



The aggregate impurity of 0"15, here indicated, is tolerably satis- 

 factory in comparison with the total quantity of gas dealt with 



