Compound of carbon and oxygen (CO2) which is sometimes used as a refrigerant. Refrigerant number R-744. [Althouse, Andrew D., Turnquist, Carl H., Bracciano, Alfred F.; Modern Refrigeration and Air Conditioning; The Goodheart-Willcox Company, Inc. South Holland, IL, 1988]
In chemistry, carbonic acid is a dibasic acid with the chemical formula H2CO3. The pure compound decomposes at temperatures greater than about −80 °C.
In biochemistry and physiology, the name "carbonic acid" is often applied to aqueous solutions of carbon dioxide, which play an important role in the bicarbonate buffer system, used to maintain acid–base homeostasis. https://en.wikipedia.org/wiki/Carbonic_acid
2. It is also known that minute bubbles of carbon dioxide (carbonic acid gas) appear in good high-spring water, if the water is exposed to the influence of light and heat. If the water is again cooled under the exclusion of light, then the bubbles disappear. The crystal-clear water, however, tastes empty and insipid even when cool. Its former full-bodied wholesomeness has therefore vanished without trace. [The Energy Evolution - Harnessing Free Energy from Nature, The Liquefaction of Coal by Means of Cold Flows]
Like the beads of carbon dioxide in water that has been warmed, through the strong influence of heat the residual substances shrivel up after the separation and precipitation of the higher quality constituents. Due to the high pressure the outer envelope or the carrier-substance will be crushed and in this way the de-energised elements released. [The Energy Evolution - Harnessing Free Energy from Nature, The Liquefaction of Coal by Means of Cold Flows]
 In the conversion of carbonic acid (H2CO3) to carbon dioxide or carbonic acid gas (CO2) with heat, molecular hydrogen (H2) is released. Therefore a kind of vacuity is created, causing a reduction in the inner 'volume'. — Ed.
 See descriptions of Patent Nos. 134543 and 138296 (pp. 201-203) and associated figures Nos. 8 and 9, p. 63 in The Water Wizard, Vol. I of the Ecotechnology series. - Ed. [The Energy Evolution - Harnessing Free Energy from Nature, The Liquefaction of Coal by Means of Cold Flows]
(2) "A process for the liquefaction of gases by the Joule–Thomson effect. In this process devised by Carl von Linde (1842-1934) for liquefying air, the air is freed of carbon dioxide and water and compressed to 150 atmospheres. The compressed gas is passed through a copper coil to an expansion nozzle within a Dewar flask. The emerging air is cooled by the Joule–Thomson effect as it expands and then passes back within a second copper coil that surrounds the first coil. Thus the expanded gas cools the incoming gas in a process that is said to be regenerative. Eventually the air is reduced to its critical temperature and, at the pressure of 150 atmospheres (well above its critical pressure), liquefies. The process is used for other gases, especially hydrogen and helium. Hydrogen has first to be cooled below its inversion temperature (see Joule–Thomson effect) using liquid air; helium has first to be cooled below its inversion temperature using liquid hydrogen." [Collins Dictionary of Science. Oxford University Press, Great Britain, 1984, ISBN 0-19-211593-6.] — Ed [The Energy Evolution - Harnessing Free Energy from Nature, The Liquefaction of Coal by Means of Cold Flows]
2. The stocks of all forms of so-called oxygen travel down the middle and with increasing cooling become inactive and shrivel up like their counterparts, the beads of carbon dioxide in warmed water. At the same time these increasingly indifferent fertilising substances (oxygen) are accelerated mechanically along the unrestricted (no guide-vanes) and shorter central axial path and are thereby dispersed, or dosed as it were. (see fig. 16) [The Energy Evolution - Harnessing Free Energy from Nature, The Liquefaction of Coal by Means of Cold Flows]