So now we come to the geochemistry of the Earth and the biochemistry of the living things upon it.
Since the 19th century, chemistry had advanced sufficiently for detailed analysis to begin in earnest. Of course, our ancestors have delved deep into the Earth since the dawn of time, emerging with flints, shells, precious metals, gems and minerals, red ochre, white chalk and black charcoal. These were the original paints, the original decorations and the earliest commerce.
We know that the Earth is separated into three distinct layers:
- The core, extending out from the centre of the planet to about half way to the surface, is primarily composed of iron.
- The mantle, which takes up most of the rest of the Earth, and is composed of iron, magnesium, silicon and oxygen.
- We live on the thin outer crust, a richly composed and variable layer full of compounds, sodium, potassium, aluminum, silicon and oxygen to name but a few. This layer also contains water and atmospheric gases.
It is assumed that the Earth was molten in the past and that centrifugal spinning over vast time epochs and cooling have caused these layers to form.
The Earth is always changing. Volcanoes erupt ejecta from the mantle, which then slowly descends back below the crust in an unceasing movement of birth, decay, melting and solidifying, constantly evolving and always changing. Chemical processes are forever on the go. Granite is comprised of sodium, potassium, aluminum and silicon, and is cooled molten rock formed in the mantle and forced upwards. Basalt is richer in iron and magnesium, and comprises most of the ocean floor, formed by lava flows under the sea. The continents are islands of silicon rich foam or spume thrown up by the blast furnace which is the underlying circulating flow of the mantle, constantly recirculating and recombining the elements of our planet.
The water and gasses were originally ejected from the Earthâ€™s interior early in its life cycle. Over time, the seas reached a balance with the revolving cycle of the minerals, as what the oceans gained in marine sediments from weathering found equilibrium with the depositions of marine sediments. This has allowed the composition of the sea to remain constant for aeons. The gasses however have varied mightily over the life span of the Earth, with vast amounts of carbon dioxide becoming locked up as a result of the development of living organisms. The actions of ultraviolet light from the sun, lightening strikes, the heat from molten lava and the chemical effects of weather have resulted in the air we have today, but gasses are volatile and can change dramatically, unlike seawater.
Weathering on the surface changes the minerals into clays, the sodium, potassium and calcium dissolving out and washing into the oceans. The more resistant minerals such as quartz (silicon dioxide) are worn down to form grains of sand. The clays and the sands combine to form soil, moved and deposited by water and rain to form sedimentary layers, which then harden into sedimentary rock. If this sedimentary rock is subject to high pressure and temperature, it will become metamorphic rock. All of these various rocks become recombined in the constant churning action of the mantle, forming new granites which rise again to the surface to get weathered all over again. Over geological time spans, the light minerals, compounds of silicon, sodium, potassium and aluminum are added to the continents, and the heavy minerals rich in iron and magnesium are resolved into the mantle.
Photosynthesis from plants converts carbon dioxide and binds it, releasing oxygen. The oxygen results in the oxidation of rocks and minerals. Cherts are formed from sea shells and skeletons, mostly comprised of silica. Chalks and limestones are formed from billions of billions of dead skeletons, coal is formed from billions and billions of dead trees. Natural gas, oil and petroleum are formed from the soft parts of billions and billions of dead animals and dead people decaying in restricted environments deep underground. Living organisms influence the chemistry of rocks and minerals as bacteria eat their way into the fabric of our Earth, changing it all over again.
We know that elements operate according to mathematical principles, see the history essay in this section on Homeopathy and Chemistry, but donâ€™t ask me to explain them! Chemistry I will tackle but maths is not my subject, sorry!
The minor elements partly follow the major elements and partly separate from them. This is how ore deposits and crystals form. Geochemistry studies how this happens. Each element crystalises or forms ore, each to its nature. The movement of water as it cools and rises to the surface results in the formation of veins and disseminated stratas in these ores. Isotopes of each element also separate out, providing information on the origins and the history of rocks and minerals by leaving a pattern of radioactive decay. This is the basis of dating, so useful for studying geology, archaeology and details of the birth of the solar system in general, as well of that of the Earth and its constituent parts.
Every element deposit leaves traces upon the Earth which can be detected according to the soils and vegetation covering them. Weathering patterns are different according to the concentrations of elements in different areas, and as such make prospecting easier, if you know what to look for. These are the trace elements which are vitally important in human and animal well being. Vegetation is a clear indicator of toxic trace elements, for example mercury in the soil. Selenium and fluorine are essential for life in trace amounts but toxic in larger concentrations. Deficiencies or excesses of trace elements can have enormous effect for life in all its forms.
Now we must return to the developments of chemistry and where we are today. Chemists group the elements into families, much as we do with our remedies.
The Halogens which are so highly reactive, they are not found free in nature but only in compounds with other elements.
The Periodic Table is the result of all that research and forms a comprehensive list to date.
For organic forms, biochemistry is of fundamental importance. Chemists ditched â€˜vitalismâ€™ or the â€˜vital forceâ€™ in the 19th century when Wohler synthesized urea, a substance known to be made only by living organisms. However, Pasteur still believed that non living matter could not give rise to the spontaneous generation of life, a form of vitalism. However, eventually Buchner won the day by proving that glucose could be fermented by a non living process in the laboratory, and the case against the vital force was closed as far as science was concerned. The door open, Sumner proved that all enzymes are simply proteins.
When the study of isotopes became a reality, individual substances in all living tissue could now be tagged and followed through all their transforms in the body. Scientists could watch in fascination as individual atoms or molecules incorporated into other forms and all the interactions could be studied. So most, if not all of the major pathways of metabolism can now be followed, including the biochemical sequences all the way through the many â€˜cyclesâ€™ of the living organism. Chemists know that proteins are polymers of amino acids linked together by peptide bonds.
Chromatography (see history of chemistry essay) allowed chemists to determine different proteins, for example milk and insulin proteins and they could then determine their three dimensional configurations. Pauling proved the helical structure of proteins, showing how enzymes work. Avery showed that the nucleic acid called DNA was responsible for heritable changes in all living organisms, and that it was contained in chromosomes.
So now we are deep into biochemical research 21st century. This is fascinating, but not illuminating for this current project: What Can Homeopaths Learn From Chemistry? I will therefore end this essay here and return to DNA at a later date when I blog about the Gengraphic Project.
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