DR. A. SCOTT OX THE COHPOSITIOX OF WATER BY VOLUHE. 
551 
existed as permanent gas, and might be either nitrogen, carbon monoxide, or hydrogen 
which had escaped combination in the relatively large excess of oxygen which usually 
was present in the final explosion. In all probability this is the real explanation of 
the permanent gas found, as the apparent impurity w^as almost always larger when 
the excess of oxygen was large than when it was small and was roughly in proportion 
Fig. 
5. 
General view of apparatus from back, with barometer turned round. 
to it. This will be easily seen on inspection of the table of results, 
examples in Series lie, we have 
Residue. Impurity. 
10'2 -3 
28‘9 *5 
41T ‘8 
Taking a few 
There are, no doubt, exceptions to this, but it seems to hold generally that the 
larger the oxygen residue the larger the impurity found as shown above. The other 
explanation which might account for the same thing is, that carbon monoxide might 
be given off easily (from the pyrogallol) to the small extent usually found, 
‘3 corresponding to an impurity of about • 34 ;Vb'b- 
1*0 
10 , 000 ‘ 
>5 
5) 
