Magnesium sparks from

Beryllium is added to copper to produce an alloy with greatly increased wear resistance it is used for current-carrying springs and non-sparking safety tools. It is also used as a neutron moderator and reflector in nuclear reactors. Much magnesium is used to prepare light nieial allo>s. other uses include the extraction of titanium (p. 370) and in the removal of oxygen and sulphur from steels calcium finds a similar use. 

Sparks created by arcs in electrical switchgear, engines, motors, or by friction (e.g. lighter spark). Aluminium, magnesium, titanium and their alloys have an affinity for oxygen and in a thermite reaction with rust produce temperatures <3000°C. A thermite flash can result from the... 

Cathodic protection systems have started a number of hydrocarbon fires, either by direct current sparking to earth, or from thermite reactions causing sparks when rusty lumps of iron fall on magnesium electrodes. 

Pyrophoric Uranium.—It has already been mentioned (p. 278) that uranium, in a very finely divided condition, takes fire on exposure to air. The black powder obtained by reduction of the oxide by means of magnesium exhibits this property. Chesneau observed that the sparks detached from uranium by friction with hard steel would ignite mixtures of methane and air, as well as such inflammable liquids as alcohol and benzene, and he concluded that their temperature could not be below 1000° C. The jjroduct obtained by Eeree (see p. 279) by heating uranium amalgam in vacuo burned spontaneously in the air. Alloys of uranium and iron containing more than 20 per cent, of uranium are pyrophoric, the activity increasing with increase in uranium content. 

Sodium nitrate gives an intense yellow light, and latterly has been used for illumination Especially in combination with magnesium it burns well without producing either cinder or sparks in wide range of the /O ratios i e the ratio can vary from 3 7 to 8 2. This is a superior characteristic, which is not available for any other composition. 

The optimum burning range with few sparks or cinders is limited from to 55 magnesium. The sodium light is larger than that of the barium light. 

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