5G6 
DE. A. SCOTT 0^^ THE COMPOSITION OF WATER BY VOLUME. 
If we omit experiment XIIT., Series IIa. 
„ „ VIIL, X., XIL, Series lie. 
,, ,, XX., XXI., Series IId. 
we get for 
]Sr umber 
of expen'ments in 
each sub-series. 
Impurity equally 
in both gases. 
Number 
of experiments. 
Impurity all in 
hydrogen. 
IIa. 
(18) 
2-0022 ±-00022 
2-0021 ±-00022 
lie. 
(^) 
2-0024 ±-00024 
2-0023 ±-00026 
IId. 
(3) 
2-00247 ±-0000033 
2-00247 ±-0000033 
which with the values above for IIb., He., gives the general mean for Series II. 
i 
i 
1 
1 
1 IL 
1 
i 
i 
i 
2-002466 ±-000003 
(46) 
2-002466 ±-000003 
Neglecting altogether Series L, as in all probalhity (as pointed out above) the 
oxygen was contaminated by chlorine, we have the values—■ 
2-002433, 
2-002466, 
as the extreme values for the number of volumes of hydrogen uniting with 1 volume 
of oxygen to form water. As Series D was a small one, especially when the two 
first experiments in it are omitted, the second value is unduly -weighted by the 
extremely small probalde error in the remaining three, I think that the value— 
2-00245, 
may he taken as the true value for the ratio sought. 
It is highly satisfactory to note that this is exactly the value found in the last 
series of twelve experiments made -with the purest gases, and the advantage of 
prolonged experience in the manipulation of these difficult and tedious experiments. 
Although the last of the ex]-)eriments was performed in April of last year, I have 
refrained from publishing the results till I could feel certain that I was unable to 
detect any further source of error, and until I felt assured that all the possible 
sources of error which have been suggested to me various friends who have taken 
an active interest in my work, had been successfully overcome or did not apply to my 
methods of manipidation and measurement. 
With regard to the results published by Morley, I think I may fairly claim that 
the simplicity of my apparatus for measuring- and preparing my gases, the fact that 
they were never transferred from one mercury trough to another, that they were 
always saturated with \vater in the same way, and that the water formed by the 
