2 ARTIFICIAL PRODUCTION OF ORGANIC COMPOUNDS. 
trative of this, three substances of volcanic origin, with 
their combining numbers: 
Sulphur, 16; selenium, 40; tellurium, 64. 
The half of the two extreme bodies gives the number of 
the intermediate one. 
So, if we take three substances met with in the waters of 
the ocean : 
Chlorine, 35; bromine, 80; iodine, 125. 
Here, again, the half of the numbers of the two extremes 
gives that of the intermediate substance. Their origin being 
the same, their properties similar, and the combining number 
being thus found, all seem to favour the idea that the middle 
elementary body may be a modified form of one of the others. 
Strange as it may appear, it is nevertheless a fact, that the 
number of the so-called chemical elements of late years has 
increased, instead of diminished. 
We have now to do with some of these elements as they 
exist in organic bodies. A few years since it w r as thought 
that the different compounds met with in a plant or animal 
could only be produced by the influence of that inscrutable 
principle termed life; that by combinations, far too recondite 
for the chemist to understand or imitate, the proximate prin¬ 
ciples found in the one or the other were alone formed. At 
the present day other views are entertained, since some of 
them may be made in the laboratory. 
The first organic principle artificially obtained was Urea. 
This was done by Wohler in 1828, who procured it by the 
application of heat to a solution of the cyanate of ammo¬ 
nia.* Anhydrous and crystallized urea contains 
c 2 h 4 o 2 n 2 , 
which are the elements of the cyanate of the oxide of 
ammonium. 
To this followed the formation of acetic acid, and the pro¬ 
duction of methyl from it by Kolbe. Since then, the consti¬ 
tution of most of the organic radicals having been 
ascertained, their preparation has been attempted, and in 
many instances success has resulted. “The labours of the 
last twelve years/’ says Fownes, “ have brought to light a 
very numerous group of substances, perfectly analogous to 
* Liebig’s process consists in dissolving cyanate of potassa in water, 
and adding to it an equal weight of neutral sulphate of ammonia, then 
evaporating to dryness. The residuum being boiled in alcohol, it 
takes up the urea, leaving the sulphate of potassa aud ammonia. The 
alcoholic solution, by evaporation, furnishes urea in the form of 
crystals. 
