By the middle of the 19th century, the source of phosphorus in natural
phosphates and the chemistry of its oxidation products had been
established. The main difficulty that had to be overcome was that these
oxidation products existed in so many forms, not only several stages of
oxidation, but, in addition, aggregations and condensations of the
phosphoric acids. Once the fundamental chemistry of these acids was
elucidated, the attention of chemists and physiologists turned to the
task of finding the actual state in which phosphorus compounds were
present in the organisms. It had been a great advance when it had been
shown that plants need phosphates in their soil. This led to the next
question concerning the materials in the body of the plant for which
phosphates were being used and into which they were incorporated.
Similarly, the knowledge that animals attain their phosphates from the
digested plant food called, in the next step of scientific inquiry, for
information on the nature of phosphates produced from this source.
The method used in this inquiry was to subject anatomically separated
parts of the organisms to chemical separations. The means for such
separations had to be more gentle than the strong heat and destructive
chemicals that had been considered adequate up to then. The
interpretation of the new results naturally relied on the general
advance of chemistry, the development of new methods for isolating
substances of little stability, of new concepts concerning the
arrangements of atoms in the molecules, and of new apparatus to measure
their rates of change.
In the system of chemistry, as it developed in the first half of the
19th century, the new development can be characterized as the turn from
inorganic to organic phosphates, from the substance of minerals and
strong chemical interactions to the components in which phosphate groups
remained combined with carbon-containing substances.
[Illustration: Figure 10.--ELECTRIC FURNACE FOR PRODUCING ELEMENTAL
PHOSPHORUS, invented by Thomas Parker of Newbridge, England, and
assigned to The Electric Construction Corporation of the same place. The
drawing is part of United States patent 482,586 (September 13, 1892).
The furnace was patented in England on October 29, 1889 (no. 17,060); in
France on June 23, 1890 (no. 206,566); in Germany on June 17, 1890 (no.
55,700); and in Italy on October 23, 1890 (no. 431). The following
explanation is cited from the U.S. patent:
Figure 1 [shown here] is a vertical section of the furnace, and Fig. 2
is a diagram to illustrate the means for regulating the electro-motive
force or quantity of current across the furnace.
F is the furnace containing the charge to be treated. It has an
inlet-hopper at _a_, with slides AA, by which the charge can be admitted
without opening communication between the interior of the furnace and
the outer air.
B is a screw conveyer by which the charge is pushed forward into the
furnace.
_c´c´_ are the electrodes, consisting of blocks or cylinders or the like
of carbon fixed in metal socket-pieces _c c_, to which the
electric-circuit wires _d_ from the dynamo D are affixed. The current,
as aforesaid, may be either continuous or alternating. _c^{2}c^{2}_ are
rods of metal or carbon, which are used to establish the electric
circuit through the furnace, the said rods being inserted into holes in
conductors _c^{3}_ (in contact with the socket-pieces _c_) and in the
furnace, as shown.
_g_ is the outlet for the gas or vapor, _h_ the slag-tap hole, and _x_
the opening for manipulating the charge, the said openings being closed
by clay or otherwise when the furnace is at work.
I use coke or other form of carbon in the charge between the electrodes
_c´_, the said coke being in contact with the said electrodes, so that
complete incandescence is insured.
A means for varying the electro-motive force or quantity of current
across the furnace with the varying resistance of the charge is
illustrated by the diagram, Fig. 2. _c´ c^{2}_ indicate the electrodes
in the furnace, as in Fig. 1, and D is the dynamo and T its terminals. E
represents the exciting-circuit. R R are resistances, and R S is the
resistance-switch, which is operated to put in more or less resistance
at R as the resistance of the charge in the furnace lessens or
increases. This switch may be automatically operated, and a suitable
arrangement for the purpose is a current-regulator such as is described
in the specification of English Letters Patent No. 14,504, of September
14, 1889, granted to William Henry Douglas and Thomas Hugh Parker.]
[Illustration:
T. PARKER.
ELECTRICAL FURNACE.
Patented Sept. 13, 1892.