One hundred years after the discovery of "cold light," the presence of
phosphorus in plants and animals was ascertained, and its form was
established as a compound of phosphoric acid. This knowledge had little
practical effect until the "nature" of the acid, in its various forms,
was explained through the work of Thomas Graham. From it, there started
a considerable technical development.
At about that time (1833), the Duke of Richmond proved that the
fertilizing value of bones resided not in the gelatin, nor in the
calcium, but in the phosphoric acid. Thus, he confirmed what Théodore de
Saussure had said in 1804, that "we have no reason to believe" that
plants can exist without phosphorus. Unknowingly at first, the farmer
had supplied this element by means of the organic fertilizers he used:
manure, excrements, bones, and horns. Now, with the value of phosphorus
known, a search began for mineral phosphates to be applied as
fertilizers. Jean Baptiste Boussingault (1802-1887), an agricultural
chemist in Lyons, traveled to Peru to see the guano deposits. Garcilaso
de la Vega (ca. 1540 to ca. 1616) noted in his history of Peru (1604)
that guano was used by the Incas as a fertilizer. Two hundred years
later, Alexander von Humboldt revived this knowledge, and Humphry Davy
wrote about the benefits of guano to the soil. Yet, the application of
this fertilizer developed only slowly, until Justus Liebig sang its
praise. Imports into England rose and far exceeded those into France
where, between 1857 and 1867, about 50,000 tons were annually received.
The other great advance in the use of phosphatic plant nutrients started
with Liebig's recommendation (1840) to treat bones with sulfuric acid
for solubilization. This idea was not entirely new; since 1832, a
production of a "superphosphate" from bones and sulfuric acid had been
in progress at Prague. At Rothamsted in 1842, John Bennet Lawes
obtained a patent on the manufacture of superphosphate. Other
manufactures in England followed and were successful, although James
Muspratt (1793-1886) at Newton lost much time and "some thousands of
pounds" on Liebig's idea of a "mineral manure."
[Illustration: Figure 8.--FLORIDA LAND-PEBBLE PHOSPHATE MINING. (From
Carroll D. Wright, _The Phosphate Industry of the United States ..._,
plate facing page 58.)]
It was difficult enough to establish the efficacy of bones and
artificially produced phosphates in promoting the growth of plants under
special conditions of soils and climate; therefore, the question as to
the action of phosphates in the growing plant was not even seriously
formulated at that time. The beneficial effects were obvious enough to
increase the use of phosphates as plant nutrients and to call for new
sources of supply. Active developments of phosphate mining and treating
started in South Carolina in 1867, and in Florida in 1888.[25]
In a reciprocal action, more phosphate application to soils stimulated
increasing research on the conditions and reactions obtaining in the
complex and varying compositions called soil. The findings of
bacteriologists made it clear that physics and chemistry had to be
amplified by biology for a real understanding of fertilizer effects.
After 1900, for example, Julius Stoklasa (1857-1936) pointed out that
bacterial action in soil solubilizes water-insoluble phosphates and
makes them available to the plants.[26]
[Illustration: Figure 9.--FLORIDA RIVER-PEBBLE PHOSPHATE MINING. (From
Carroll D. Wright, _The Phosphate Industry of the United States ..._,
plate facing page 64.)]
The insight into the importance of phosphorus in organisms, especially
since Liebig's time, is reflected in the work of Friedrich Nietzsche
(1844-1900). This "re-valuator of all values" who modestly said of
himself: "I am dynamite!" once explained the human temperaments as
caused by the inorganic salts they contain: "The differences in
temperament are perhaps caused more by the different distribution and
quantities of the inorganic salts than by everything else. Bilious
people have too little sodium sulfate, the melancholics are lacking in
potassium sulfate and phosphate; too little calcium phosphate in the
phlegmatics. Courageous natures have an excess of iron phosphate." (See
volume 12 of _Nietzsche's Works_, edit. Naumann-Kröner, Leipzig, 1886.)
In this strange association of inorganic salts with human temperaments,
the role of iron phosphate as a producer of courage is particularly
interesting. What would a modern philosopher conclude if he followed the
development of insight into the composition and function of complex
phosphate compounds in organisms?