When it comes to the amount of Mercury you discuss, are you indicating that ancient man existing at the time the stone liths at Stonehenge could have obtained the Mercury, or are you discussing current times.
However, your foregoing ideas raise two interesting points. They are mercury's extreme toxicity and the ease with which the amount of mercury you require, some 100 liters, in your posit could be obtained.
Mercury (Hg) is a heavy metal element. 100 liters of mercury, where 1 liter of mercury = 13.53 kg, would weigh 1,353 kg, or 2,982.854 pounds - almost 3 tons.
It exists in three forms: elemental, inorganic, and organic. All three of these forms of mercury can be toxic, causing several health problems.
Elemental mercury is a silver colored liquid that is used in old thermometers, artisan will gold mining, dentistry, and certain other industries. It is poorly absorbed through the skin or G.I. tract but elemental mercury vapors are readily absorbed by the lungs.
Inorganic mercury in certain industries and laboratories—serious exposures are rare. In the United States, most mercury exposure occurs in the form of organic mercury, specifically the consumption of Mercury contaminated fish.
Normal whole blood mercury is usually <10 ng/mL. People who work in certain occupations may have levels up to 15 ng/mL routinely. A value greater than 50 ng/mL usually indicates significant mercury exposure.
Mercury has been found in Egyptian tombs dating to about 1500 B.C. , and it was probably used for cosmetic and medicinal purposes even earlier. In about 350 B.C. , the Greek philosopher and scientist Aristotle described how cinnabar ore was heated to extract mercury for religious ceremonies. The Romans used mercury for a variety of purposes and gave it the name hydrargyrum, meaning liquid silver, from which the chemical symbol for mercury, Hg, is derived.
Mercury is extracted from ores - one of the main varieties being cinnabar. It is found mostly in China, Spain and California. Droplets of liquid mercury can actually be found within the ore, though it is usually extracted through heating. Mercury vapour then forms in a condensation column from which the liquid is collected when it cools.
Demand for mercury greatly increased in 1557 with the development of a process that used mercury to extract silver from its ore. The mercury barometer was invented by Torricelli in 1643, followed by the invention of the mercury thermometer by Fahrenheit in 1714. The first use of a mercury alloy, or amalgam, as a tooth filling in dentistry was in 1828, although concerns over the toxic nature of mercury prevented the widespread use of this new technique. It wasn't until 1895 that experimental work by G.V. Black showed that amalgam fillings were safe, although 100 years later scientists were still debating that point.
There is some interconversion in vivo between the various forms of mercury. Inhaled elemental mercury vapor, for example, is easily absorbed through mucus membranes and the lung and rapidly oxidized to other forms (but not so quickly as to prevent considerable deposition of elemental mercury in the brain). Methyl mercury is easily absorbed through the gut and deposits in many tissues, but does not cross the blood-brain barrier as efficiently as elemental mercury; however, on entering the brain it is progressively demethylated to elemental mercury. Mercury salts, in contrast, tend to be insoluble, relatively stable, and poorly absorbed.
Human toxicity varies with the form of mercury, the dose and the rate of exposure. The target organ for inhaled mercury vapor is primarily the brain. Mercurous and mercuric salts chiefly damage the gut lining and kidney, while methyl mercury is widely distributed throughout the body.
Mercury toxicity varies with dosage: large acute exposures to elemental mercury vapor induce severe pneumonitis, which in extreme cases can be fatal. Low-grade chronic exposure to elemental or other forms of mercury induces subtler symptoms and clinical findings, as discussed hereinafter.
A less common source of mercury vapor is spilled mercury, and there is a report in the literature of Idiopathic Thrombocytopenic Purpura caused by vacuuming spilled mercury (thereby producing a major acute exposure to mercury vapor).
Methyl and dimethyl mercury (organic mercury) usually originate from biological sources, chiefly fresh or salt water fish. Over three thousand lakes in the United States have been closed to fishing due to mercury contamination and many species of ocean fish are also tainted with considerable concentrations of mercury.
In addition to the brain, metallic mercury is also deposited in the thyroid, breast, myocardium, muscles, adrenals, liver, kidneys, skin, sweat glands, pancreas, lungs, salivary glands, testes, and prostate and may be associated with dysfunction of those organs. Mercury also has affinity for binding sites on the surface of T cells* and for sulfhydryl groups influencing T cell function. Mercury deposits readily in placenta and fetal tissues and is found in breast milk.
* T cells: also called T lymphocyte, is a type of leukocyte
(white blood cell) that is an essential part of the immune system
. T cells are one of two primary types of lymphocytes
being the second type—that determine the specificity of immune response to antigens
(foreign substances) in the body.
T cells originate in the bone marrow
and mature in the thymus
. In the thymus, T cells multiply and differentiate
, or cytotoxic T cells
or become memory T cells
. They are then sent to peripheral tissues
or circulate in the blood
or lymphatic system
. Once stimulated by the appropriate antigen
, helper T cells secrete chemical messengers called cytokines
, which stimulate the differentiation of B cells into plasma cells
-producing cells). Regulatory T cells act to control immune reactions, hence their name. Cytotoxic T cells, which are activated by various cytokines, bind to and kill infected cells and cancer
From my standpoint, accumulating enough mercury (Hg) to perform your mentioned processes would be extremely difficult and, at the same time, extremely toxic. Regardless of mercury's ability to float or provide a viscous surface to slide objects of a sufficient size, it strikes me that it would be impractical at any historic age.