90 
FLORIDA STATE HORTICULTURAL SOCIETY. 
showed that electric sparks under certain 
conditions oxidized atmospheric nitro¬ 
gen. 
Later the noted chemist Bunsen did 
more valuable work in the electro-ther¬ 
mic fixation of atmospheric nitrogen. 
Until very recently the yield of oxides 
of nitrogen has been very poor by elec¬ 
tro-thermic methods being only in the 
experimental stage. The principles upon 
which are based all electro-thermic meth¬ 
ods for the fixation of free nitrogen are 
in general as follows: 
When air is subjected to silent electri¬ 
cal discharges of high potential, the oxy¬ 
gen is ozonized and the nitrogen is oxi¬ 
dized most largely into nitric and dinitric 
oxides (NO, NO2) the former can be fur¬ 
ther oxidized to dinitric oxide. 
Dinitric oxide or nitrogen preoxide in 
the presence of water forms nitric (HN 
Da) nitrous acid (HN O2) as well as ni¬ 
tric oxide (NO) depending on the relative 
proportions of peroxide and water pres¬ 
ent. 
These acids, nitric and nitrous, com¬ 
bine with bases to form nitrates and ni¬ 
trites. 
To oxidize nitrogen requires a very 
high temperature. It has been shown in 
recent years, that the percentage of ni¬ 
trogen oxidized is very largely depend¬ 
ant upon the temperature the gases are 
exposed to. Nernst determined that at 
1,811 degrees C. only .37 per cent, of the 
Nitrogen supplied was oxidized, while at 
3,200 degrees C. 5 per cent, of the nitro¬ 
gen was oxidized. 
If the oxides fromed are not rapidly re¬ 
moved, this high temperature causes their 
decomposition. 
Electricity is the best source of heat 
for obtaining the high temperature re¬ 
quired for the oxidization of atmospherit 
nitrogen. 
Of the large number of electro-thermic 
methods for the fixing of free nitrogen, 
but one, the Birkeland-Eyde process, has 
proven a complete commercial success. 
In the Birkeland-Eyde process the in¬ 
ventors use magnetic blow-pipe electrodes 
with an alternating current, this gives a 
flame disk of large surface. 
The air enters from both sides of the 
flame disk and is drawn off from below 
in such a manner that it has passed direct¬ 
ly through the plane of the flame. 
Only about two percent, of the nitro¬ 
gen is oxidized in the flame. After pas¬ 
sing through the flame, the air is cooled 
in a suitable chamber where the nitric 
oxide (NO) is further oxidized to per¬ 
oxide, (NO2.) From the cooling chamber 
the gases are conducted through absorp¬ 
tion towers, eight in number, where they 
come in contact with water. The dilute 
nitric acid is drawn off from below, rais¬ 
ed again, and allowed to trickle down 
again from tower to tower, until upon 
flowing from tower number eight the 
formerly very dilute acid has been raised 
to about 50 per cent. 
The last traces of acid are removed in 
towers irrigated with lime water and 
finally in a dry lime chamber. 
The nitric acid thus obtained is neu¬ 
tralized with calcium carbonate (lime¬ 
stone) Ca CO3, and the resulting calcium 
nitrate (Ca NO3,) is evaporated and fused 
using the waste heat from the electric 
furnace. 
The factory at Nottodden, Sweden 
using the Birkeland-Eyde process, obtains 
a yield of from ii to 13 hundred pounds 
of nitric acid per killowatt year, equiva¬ 
lent to about I T-3 horse power year. 
