Burned wood

When wood bums in air, the carbon and hydrogen in the wood combine with oxygen in the air and are converted to carbon dioxide and water. When cellulose burns, for example, the following reaction takes place  

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Wood ash generally contains calcium, potassium, phosphoms, magnesium, and siUca. Ashes recovered from burned wood are - 25% water soluble and the extract is strongly alkaline. The ash fusion temperature is in the range of 1300 to 1500°C. 

Air pollution, associated with burning wood in Tutbury Castle in Nottingham, was considered "unendurable" by Eleanor of Aquitaine, the wife of King Henry II of England, and caused her to move in the year 1157. One... 

Considerable heat is generated. Many volatile substances liberate heat at a rate some ten times faster than burning wood. 

The two major ways by which humans get energy is to either burn fossil fuels or to burn wood for fuel. Both contribute substantially to air pollution, and both can have serious effects on (1) the health of plants and animals and (2) the workings of Earth s atmosphere. 

Industries that burn wood, gas, oil or coal contribute most of the rest of airborne B(a)P. Studies on animals have shown that contact with BaP and PAH can cause skin cancer, but the effects of breathing or ingesting them are not yet well enough studied to draw a conclusion as to other cancers. Animal tests have shown that exposure to BaP may cause reproduction difficulty. The U.S. government considers BaP a human carcinogen. 

The choice of alkali was more difficult. In Leblanc s time, the alkali was generally a carbonate (C03) or hydroxide (OH) of potassium or sodium extracted from the ashes of salt-rich plants. For example, northerners made an odoriferous soft soap by burning wood and boiling its ashes with animal fat or fish oil. In Spain, Marseilles, Genoa, and Venice, hard Castile soap was made by boiling olive oil with the ashes of seaweed and shore plants. 

The burning process leaves very little solid remains only ash, made up of inorganic salts that rarely make up more than a few percent of the total mass of wood. When wood bums with a restricted supply of air, however, and there is insufficient oxygen to combine with all the carbon in the wood, the remains are made up of charcoal, a very porous and impure form of carbon. Charcoal is extremely stable it does not decay, nor is it altered by most microorganisms, and it may be preserved for very long periods of time charcoal often also preserves the morphology of the burned wood. Because of its stability, charcoal residues are often found in archaeological sites where wood was either used as fuel or otherwise burned. 

After ignition of the edge, the external heat flux is removed and it is no longer felt by the wood, in any way. A researcher measures the heat flux of the flame, ahead of the burning wood, as it spreads steadily and horizontally along the edge. That measurement is depicted in the plot below. Compute the flame speed on the wood, based on this measurement. 

As with other alkali metals, potassium compounds have many uses. For example, almost all of the compound potassium chloride is used in fertilizers. Currently potassium chloride is mined or derived from seawater. Many years ago, potassium was secured for human use by burning wood and plant matter in pots to produce an ash called potash, which was mostly potassium carbonate and used as a caustic, mainly for making soap when mixed with fats. 

Another consideration in flames is radiatioiL The light that one sees in a flame is mostly fluorescence from the radiation of particular radical species formed in electronically excited states. (The blue color from CH4 flames is CH emission.) Gases also radiate blackbody radiation, primarily in the infiared. The glow from burning wood or coal is blackbody emission radiated from the surface. 

Recall that the emission observed from cracks in a burning wood surface is brighter because the emission from a cavity has the equilibrium blackbody distribution, which is independent of the emissvity of the surface. Also recall that most of the heat from a campfire... 

Carbon monoxide is found in varying concentrations in unventilated and confined spaces resulting from partial oxidation of carbonaceous matter. Burning wood, paper, kerosene, or other organic materials in inadequate air can produce this gas. It also is found in automobile exhaust and tobacco smoke emissions. 

Potash was made on a small scale in New England in the seventeenth century, and for two centuries American potash and pearlash, made by burning wood and leaching the ashes, were shipped to European countries, with incalculable loss to American agriculture (50). 

Ramdahl, T., I. Alfheim, S. Rustad, and T. Olsen, Chemical and Biological Characterization of Emissions from Small Residential Stoves Burning Wood and Charcoal, Chemosphere, 11, 601-611 (1982a). 

Samuel Hopkins modifies the method for burning wood to make potash and is issued the first United States patent in 1790. 

Under ordinary circumstances crops cannot be specially grown for the sake of their potash since the soil would be rapidly depleted of this valuable constituent. In special districts, however, it may be profitable to burn wood in pits sheltered from the wind, and extract the ashes with water. 

The above data show that FGAN is not abnormally sensitive to initiation by impact, friction or heat, but the molten FGAN is much more sensitive than the cryst material. However, a 52-lb wt allowed to fall 10 ft on a mixt of molten FGAN and-bagging paper confined in a steel tube caused no expln. The impact on,and immersion in similar mixes of burning wood or charcoal also failed to cause deton of FGAN, The probability of expln by impact on molten FGAN appears to be unlikely... 

Carbon Manufacture. The history of Chinese ink indicates that the carbon was made in at least two ways—viz., by burning wood, usually pine, or by burning oil. However, other fuels may also have been used. 

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