Biomedical Engineering Reference
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out the adhering acid is joined with what was before decanted
of, and the whole is gradually evaporated; the diſſolved ſulphat of
lime criſtallizes in form of ſilky threads, which are removed, and by
continuing the evaporation we procure the phoſphoric acid under
the appearance of a white pellucid glaſs. When this is powdered, and
mixed with one third its weight of charcoal, we procure very pure
phoſphorus by ſublimation.” (p. 206).
8.3
Chemical Investigations on Calcium
Orthophosphates in the 19
th
Century and
the First Half of the 20
th
Century
century, various investigations of calcium apatites and
other calcium orthophosphates were performed by Jöns Jacob
Berzelius (1779-1848) [18, 19], M. Baruel [20], C. Morfit [21], Robert
Warington (there were 2 chemists with this name, presumably, a
father (1807-1867) and a son (1838-1907)), who performed the
earliest well documented systematic studies of the outstanding
quality [22-25], and R. Fresenius [26]. Furthermore, a German
chemist Eilhard Mitscherlich (1794-1863) also worked in this area
(unfortunately, I failed to find any reference to his publications).
To provide some proofs of this statement, let me cite a paragraph
from Ref. [23]: “Mitscherlich tells us, that when chloride of calcium
is added to ordinary disodic phosphate, the latter being maintained
in excess, the precipitate formed is tricalcic phosphate, while the
solution becomes acid from the production of monosodic phosphate.
Berzelius, on the contrary, states, that the precipitate formed under
these conditions is not tricalcic phosphate, but the octocalcic
triphosphate, which lie has elsewhere described. All experimenters
agree, that when the operation is reversed, and discc1.c. phosphate is
poured into an excess of chloride of calcium, the precipitate is neither
tricalcic nor octocalcic, but dicalcic phosphate.” (pp. 296-297). Thus,
TCP, DCP and OCP have been known since, at least, 1866, while in
fact a bit earlier. Furthermore, the standard preparation procedure
of the sparingly soluble calcium orthophosphates has been known
since the same time.
Among the available publications written by two Robert
Waringtons [22-25], Ref. [23] by Robert Warington Jr. deserves both
a special attention and extensive citations. For example, to prove,
In the 19
th
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