Biomedical Engineering Reference
In-Depth Information
CDHA) to the stoichiometric HA under continuous (up to 50 hours)
boiling in distilled water. From the results of numerous chemical
analyses the author concluded that during boiling an aqueous
suspension of the TCP was slowly transformed to a suspension of
3Ca
., HA-see Table 1.1) and soluble acidic calcium
orthophosphates. The following conclusion was made: “Since it
appears that all phosphates of calcium less basic than apatite are
unstable under the continued action of pure water, it seems probable
that a more exact examination of natural phosphates would show
that many phosphates now regarded as tricalcic are in fact of a more
basic nature.” (p. 989). Thus, the apatitic nature of the majority of
natural calcium orthophosphates has been predicted in 1873. The
next available study on the TCP hydrolysis was published in 1929
only [27].
To give the appropriate tribute to other researchers, one should
mention that existence of acidic calcium orthophosphates, currently
known as MCP and DCP (it is impossible to discover, whether they
were hydrated or anhydrous), has been known, since, at least 1806:
“In this way were distinguished among the salts two combinations,
one neutral, and one with an excess of acid; and these were
supposed to be determinate, as in sulphate and super-sulphate of
potassa, or the phosphate and super-phosphate of lime.” [28, p. 38].
Furthermore, in 1849, it was written that “M. J. L. Lassaigne, at the
meeting of the Academy of Sciences of Paris, of the 15th January,
presented a memoir upon this subject, showing by experiments
that the phosphate and carbonate of lime are introduced into plants
in solution in water containing carbonic acid, which had before
been shown as to the phosphate by M. Dumas, and has long been
known as to the carbonate.” [29]. Thus, a higher solubility of both
calcium orthophosphates and calcium carbonate in weak acids was
already known in 1849. The first accessible paper on detection
and preservation techniques of various deposits, including calcium
orthophosphates, was published shortly afterwards [30]. Presence of
calcium orthophosphates in teakwood was established in 1862 [31].
Various analytical topics on calcium orthophosphate chemistry has
been studied since, at least, 1863 [32] and remained to be a subject of
active research approx. until the 1910s [33-42]. A popular fertilizer
superphosphate, which represents “a mixture of the last-mentioned
compound and sulphate of lime” [43] has been known since, at least,
1868 [44]. More than 20 research papers on superphosphate were
P
O
.CaOH
O (
i.e
3
2
8
2
Search WWH ::
Custom Search