Bums

Flammability limits. A flammable gas will bum in air only over a limited range of composition. Below a certain concentration of the flammable gas, the lower flammability limit, the mixture is too lean to burn, i.e., lacks fuel. Above a certain concentration, the upper flammability limit, it is too rich to burn, i.e., lacks oxygen. Concentrations between these limits constitute the flammable range. 

The application of WIROTEST 202 device with high frequency magnetic currents, will allow for simultaneous detection of parts with bums, which can occur during grinding. 

Chemically, carbon dioxide is not very reactive, and it is often used as an inactive gas to replace air when the latter might interact with a substance, for example in the preparation of chromium II) salts (p. 383). Very reactive metals, for example the alkali metals and magnesium can, however, continue to bum in carbon dioxide if heated sufficiently, for example... 

Using the apparatus shown in Figure 9.3 it can be shown that ammonia gas will bum in chlorine gas, the ignition being spontaneous in this case ... 

Hydrazine, unlike ammonia, will bum in air with evolution of much heat ... 

Once this reaction has been initiated, it supports the combustion of many substances since they can bum in the liberated oxygen. In this respect, it is hardly distinguishable from oxygen itself but other properties serve to distinguish the two gases (see Table 9.J). 

Other examples of water as an apparent catalyst are (a) carbon monoxide will not bum in oxygen unless a trace of water is present. 

Hydrogen sulphide bums in air with a blue flame yielding sulphur dioxide, but if the air supply is limited, preferential combustion to form sulphur occurs ... 

In the presence of charcoal, chlorine and hydrogen combine rapidly, but without explosion, in the dark. A jet of hydrogen will bum in chlorine with a silvery flame and vice versa. 

Anhydrous hydrogen chloride is not particularly reactive, either as a gas at ordinary temperatures, or a liquid (b.p. 188 K) and does not react with metals such as iron or zinc, nor with dry oxides. A few reactive metals such as sodium, will bum in the gas to give the chloride and hydrogen ... 

Alcohols.—Bums rapidly with a clear flame. Typical of many aliphatic substances. 

Note, (i) Care should be taken to distinguish between a residue of carbon which may be very difficult to bum off completely, and a really non-volatile residue due to the presence of a metallic derivative. Thus for instance starch leaves a hard black residue of carbon which can best be burned away by moistening with a saturated solution of ammonium nitrate and then reheating. 

CAUTION. Bromine must be handled with great care and in the fume cupboard. The liquid produces painful bums and the vapour is unpleasant. Bromine bums should be treated immediately with a liberal quantity of glycerine. If the vapour is inhaled, relief may be obtained by soaking a handkerchief in alcohol and holding it near the nose. 

Bromoacetic acid must not be allowed to come into contact with the hands as it causes serious bums. 

CAUTION. Phenylhydrazine is highly poisonous and produces unpleasant bums in contact with the skin. Wash off immediately any liquid which has come into contact with the skin first with 2 per cent, acetic acid, then with soap and water. 

Aromatic carboxylic acids are usually crystalline sohds, bum with a smoky flame, and are generally sparingly soluble in water. They may be detected and characterised as already described under Aliphatic Carboxylic Acids (Section 111,85). 

Burns caused by dry heat (e.g., by flames, hot objects, etc.). For slight bums in which the skin is not broken, apply tannic acid jelly ( Tannafax ), acriflavine jelly ( Bumol ) or butesin picrate ointment (butesin is re-butyl J aminobenzoate). 

For larger burns, or bums in which the skin is reddened or blistered, apply one per cent, sodium bicarbonate solution without delay, and call for medical aid at once. 

Acids on the skin. Wash immediately and thoroughly with a liberal quantity of water, then with saturated sodium bicarbonate solution, and finally with water. For a serious acid bum, follow this by applying a disinfectant, drying the skin and covering with acriflavine jelly. 

In operation, a spark source is normally first flushed with argon to remove loose particulate matter from any previous analysis. The argon flow is then reduced, and the cathode is preheated or conditioned with a short bum time (about 20 sec). The argon flow is then reduced once more, and the source is ran for sufficient time to build a signal from the sample. The spark is then stopped, and the process is repeated as many times as necessary to obtain a consistent series of analyses. The arc source operates continuously, and sample signal can be taken over long periods of time. 

Burlap bags Burner acid Burning behavior Burning tires Burnout agents Bums... 

When ignited, nonfilled acetal resins bum in air with a characteristic dull blue flame. 

Acetic anhydride penetrates the skin quickly and painfully forming bums and bUsters that are slow to heal. Anhydride is especially dangerous to the deUcate tissues of the eyes, ears, nose, and mouth. The odor threshold is 0.49 mg/m, but the eyes are affected by as Httie as 0.36 mg/m and electroencephalogram patterns are altered by only 0.18 mg/m. When handling acetic anhydride, mbber gloves that are free of pinholes are recommended for the hands, as well as plastic goggles for the eyes, and face-masks to cover the face and ears. 

Dichloroacetic acid is used in the synthesis of chloramphenicol [56-75-7] and aHantoin [97-59-6]. Dichloroacetic acid has vimcidal and fungicidal activity. It was found to be active against several staphylococci (36). The oral toxicity is low the LD q in rats is 4.48 g/kg. It can, however, cause caustic bums of the skin and eyes and the vapors are very irritating and injurious (28). 

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