28 
FACTS AND OBSERVATIONS. 
the Other hand, does deoxidation, whether effected in the 
living organism or the chemical laboratory, tend to combine 
the separated atoms into comparatively complex molecules, 
the residues of which become banded together into still 
more complex conglomerate molecules. In broad antagonism 
to the doctrines held but very recently as indisputable, it is 
now known that the chemist, like the plant, is capable of pro¬ 
ducing from carbonic and water a host of organic bodies; 
and there seems no reason to question his capability of 
ultimately reproducing all animal and vegetable principles 
whatever. 
H EAT AS AN Analyser. —M. Plucker is of opinion 
that no compound body in a gaseous state can escape decom¬ 
position, if we augment its temperature sufficiently. 
To effect this, he says, we introduce the gaseous body into 
a Geissler tube; then we heat the minute thread of gas in its 
capillary portion by means of an induction current, and 
examine the incandescent thread with a prism. 
In two experiments with tubes containing carbonic acid 
and carbonic oxide, he gave to the gases a pressure of 100 
millimetres, and illuminated them with discharges of a large 
Ruhmkorff coil. In discharging the apparatus in an ordinary 
way, he obtained the ordinary spectrum of carbonic oxide; 
but upon interposing a Leyden jar, instantly was seen 
the beautiful spectrum of oxygen. He therefore concludes 
that at a lower temperature the carbonic acid is resolved into 
carbon and carbonic oxide, and at a higher one this latter gas 
itself is decomposed. Nor is this all, for immediately after 
the decomposition the temperature falls, and the recomposi¬ 
tion of oxygen and carbon ensues. 
In another experiment M. Plucker took chloride of zinc. 
Having introduced a small quantity into the spectrum tube, 
and made the vacuum as perfect as possible, on heating the 
tube, first the chlorine spectrum is seen, slightly developed, 
but easily recognisable. Continuing to heat the gas, this 
spectrum, whicli at first augments in intensity, gradually 
disappears, and that of metallic zinc comes into view. If the 
tube be now permitted to cool, the phenomena are observed to 
take place in inverse order; the zinc spectrum disappearing 
first, and this replaced by that of chlorine. 
In citing these examples of decomposition of bodies, as 
evidenced by spectral analysis, M. Plucker states the de¬ 
composition of the vapour of water in the tubes must not be 
passed over. And, he adds, the essential character of the 
analysis thus sketched is that it not only enables us to recognise 
