CHEMISTRY. 3] 
sugar we shall obtain indirectly the amount of oxygen in the sugar, thus 
completing our knowledge of its components. However complicated the 
preceding manipulations may appear, nevertheless, by properly observing 
all the conditions necessary, very accurate results may be obtained. 
_ A special mode of treatment is required in the case of certain liquid and 
at the same time volatile organic matters, as alcohol, which cannot be mixed 
with oxyde of copper without loss. These are inclosed in little glass bulbs 
drawn out into a long tail, and one or two of these bulbs filled with the 
substance in question are laid in the combustion tube, as shown in pl. 31, fig. 
27. The bulbs are covered with oxyde of copper, the tails being broken 
off. The rest of the operation is as in the case of dry organic matter. To 
the question which is answered by the analysis of a volatile organic body, 
there is almost always united another with respect to the specific gravity of 
its vapor, so that the determination of this always accompanies the analysis. 
For this purpose we make use of a balloon (fig. 41) provided with a long 
tube bent nearly at right angles. After weighing this with the inclosed air 
we pour in enough of the liquid, the density of whose vapor is to be ascer- 
tained, for the volume of the vapor generated to exceed the volume of the 
balloon. This is then fastened by wire to the post, A (fig. 40), carried by 
the holder, D, and the balloon immersed in the oil bath, B, whose temperature 
is observed by means of the thermometer, a. The oil bath is heated by the 
furnace, C, to above the boiling point of the liquid in question, and at the 
moment when all the liquid in the balloon has been converted into vapor, 
the point of the tube is melted together by a blowpipe. The balloon is then 
allowed to cool and again weighed. Its present weight is that of the balloon 
and the contained vapor, which has driven out all the air ; the former weight 
was that of the balloon and the contained air. The volume of the balloon 
is determined by filling with distilled water and weighing. We can readily 
ascertain the volume occupied by a known weight of distilled water, and 
consequently the volume of our balloon, and hence also the weight of the 
included air of the empty balloon. Thus we. get the weight of the vapor 
which occupies the same space as the air of the balloon. 
There are numerous substances which do not completely burn with oxyde 
of copper alone. For such we can make use of a current of oxygen which 
may be passed over the oxyde of copper during the combustion. As the 
whole process and its accompaniments are much as we have already 
described, we shall here only mention the apparatus especially necessary. 
In pl. 31, fig. 33, AA represents a gasometer filled with oxygen gas. Next 
to it is a gasometer filled with air, communicating with the tube, C, through 
a tube, c, so that by opening the proper cocks, either oxygen or air may be 
allowed to pass through the apparatus. The tube, C, carries the gas into 
the bottle, D, containing sulphuric acid, and from this into the potash 
apparatus ; both these vessels, with their contents, are intended to free the 
oxygen and the air from the watery vapor which may have been dissolved 
in them. The combustion tube, I, which contains the substance to be 
burned, mixed with oxyde of copper as before, is heated by means of a 
brass spirit lamp, PP. Enough spirit is poured into the cup, M, to fill the 
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