Gerhardt’s Organic Chemistry. 95 
We cannot retrace this process and bringing together the formic 
acid, carbonic acid and water, by a process of dexoydation re- 
produce the sugar. ‘These products were formed by a combus- 
tion in which a part of the carbon and hydrogen is converted 
into carbonic acid and water, and the power of reducing them 
belongs to the vegetable organism, where the chemical affini- 
ties are controlled and directed in a peculiar way by the vital 
orce. It is thus that in these operations, we commence with 
acomplex body and by a process in which its carbon and hy- 
drogen are gradually oxydized, reduce it to simpler and simpler 
‘orms. 
There are however some exceptions to this law; a few s 
thetical processes are known by which we can unite the ele- 
ments of simpler compounds to form one more complex. ‘T'wo 
polymeric bodies are known which are formed by a grouping to- 
gether of several molecules of aldehyde; and many of the essen- 
tial oils undergo a similar change by action of sulphuric acid. 
The decomposition of organic substances by heat oflers some re- 
markable instances of this kind; in the dry distillation of wax 
C,,H.,O, we obtain paraffine, which is C, ,H, ,. 
In view of these relations, observes our author, ‘we may con- 
sider all organic substances as the result of the combustion of 
others more ridh in carbon and hydrogen, or reciprocally as the 
products of the reduction or complication of other bodies contain- 
ing less carbon and hydrogen.” 
“Tn considering from this point of view the whole of organic 
substances, we observe that they offer successive and alm - 
In the examination of organic substances, we observe that 
those which correspond in their chemical characteristics, present 
4 similarity of relation in the proportions of their constituent 
elements. The alcohols, embracing wood-spirit, spirit of wine, 
