TROUSERS EXPLODE

NOT THEIE FAULT

WEED-KILLER DANGERS

SODIUM CHLORATE

. Not long ago, in a country township, a man's pair of trousers exploded with a loud report. Fortunately the owner was not in them at the time.' He was, however, in the same room, and, although dazed by the force of the-ex-plosion, he was able to seize the garment, which was. hanging before the fire, and hurl it out on to the grass outside. There the trousers smouldered, with a series of minor detonations. _ This strange behaviour of a quite respectable garment was due to the fact that its owner had been spraying .sodium chlorate on ragwort, and mci: dentally had sprayed some on his trousers. Clothing and other burnable substances become highly inflammable when they absorb sodium chlorate. When clothes take the spray, the water evaporates rapidly, leaving the chlorate distributed through the fibres of the cloth. There is nothing visible to warn tho owner that the affected portion of the dried-out clothing may catch fire (or even explode) by coming 'near -a fire (there need not, be actual with flame or spark), or by friction, or by the concussion of a sudden' blow. Even sun-heat can cause ignition or explosion ofi clothes affected by sodium chlorate. ' There have been at least two deaths from such cause. FIRE CAN'T BE SMOTHERED. Easy ignition is only half the danger. To suppress a sodium chlorate fire is as'difficult as to,start it is easy. Reason —it is rich in oxygen. Oxygen is present in atmospheric air .only to the extent of about one-fifth of its volume. But sodium chlorate contains as much as 45. per cent, of available oxygen. Therefore one cannot rely on stopping a sodium chlorate fire by smothering it. ■ ;■._."_ Explaining this point the chief chemist of tho Department of Agriculture (Mr. B. 0. Aston), writing in the "Journal of " Agriculture," states: " When combustible matters burn in ordinary air, it is due to the matters., or the air, being raised to a temperature sufficiently high to enable chemical combinationto take place between the two. The' air must therefore be in contact with the substance to be burned, and fresh supplies of air must be continuously available if burning is to continue. By cutting off the supply of air the burning is checked, and if the exclusion is complete the fire is extinguished. ■ Ordinarily', when a person's clothes catch fire the quickest way to extinguish the flames is to wrap the patient closely in a- blanket, rug, mat, carpet, sack, or even a bystander's coat in order to cut off the air and oxygen supply. In the burning of chlorate-saturated clothes the oxygen is already present in such intimate contact with the material that the ignition is extremely rapid. Wrapping the subject up may not hinder the" combination of the oxygen from the chlorate with i|.e combustible matter of the clothing. . One would prefer,to advise work6rs to wear such loose clothing in such a wAy that^in emergency these could be,, stripped off. with the least possible delay. Actually the combustion of the chlorate-saturated portion is so nearly instantaneous that there is no time for preventive measures once the fire is started.", . ".. ....- . ....... AS AN EXPLOSIVE, ILLEGAL. ' The Department of Agriculture warns users of weed-killers, and users of chlorate weed-killer that .has-been illegally converted into explosive, and the public generally, that sodium chlorate should not come into contact with ordinary clothes, woodwork, sacking, dry fodder, or any other' combustible substances, that it should bo kept stored in the original iron containers, and only mixed and transported in metal tf>r enamelled vessels, which must afterwards be thoroughly washed out with water. It is necessary that the cloth-, ing worn, .by workers when, using chlorate be; of waterproofed material arid gumboots, which can' be easily and quickly washed free from, any chlorate after spraying is .finished for the day. Similarly, that all woodwork portions of implements used ■in handling the sodium chlorate or solution be "kept waterproof by paint in order to facilitate washing down with water. It is an offence against the Explosives Act to mix chlorates with other substances with the intention of making an explosive. It is an offence against" the Postal Regulations, to send a dangerous' subr> stance through the mails,. the penalty being two years' imprisonment or a,fine of fifty pounds (£SO), or both. SUGAR-LIKE CRYSTALS. j The Government, having introduced tho idea of exterminating weeds by chlorate, cannot-afford to countenance, any way of using it which may prove dangerous. It is a new experience, to. farmers that the innocen.t-looking sugarlike .crystals should,' on being mixed and heated or rubbed with v organic materials such as clothing, woodwork, flooring, pelts, bagging, ■ casks,, hay, chaff, .flour, .wooden .floors of railway trucks or sheds, or anything burnable, cause an outburst of flames practically impossible to quench in time to avoid extensive injury. Certain modern inventions, like high explosives and flying machines, provide roorii for only one' mistake, unless the-experimenter is lucky. ' The difficulties of transporting sodium chlorate are increased by the fact that it cannot be contained in combustible bagging, casks, or barrels without- danger, and should be carried only in iron railway trucks, since a leakage on to a wooden truck floor would be dangerous and difficult to remedy entirely. The only holding vessels'should be of metal (not galvanised or zinc-lined), and should be thoroughly washed'out when empty. Commercial sodium is like, yet very unlike, its relative, common salt. The first is NaClO3, the second is .NaCl. Both are small white crystals. Potassium chlorate - (KCIO3), like sodium chlorate, .is explosive. The former is much more soluble and therefore sprayable. These chlorates are made by the action of chlorate on caustic soda or caustic potash. The raw materials are not available in New Zealand at present. The chlorates are imported from U.S.A., Sweden, France, and other countries. ' ' • ■ The first purpose of importing sodium chlorate is to fight ragwort, a national menace. If no better wecd-luller isfound, then obviously tho use of sodium chlorate will bo widespread. Washing chlorate-affected clothes, if done in the ordinary washing way, increases risk by'distributing-the chlorate. Rinsing in a succession of waters, or immersing in running water, is preferred. ■