Ignition temperature aqueous solutions

According to Sudo [96] lead azide prepared by the action of sodium azide on an aqueous solution of lead acetate has a lower ignition temperature (332-336°C) than that obtained by the action on a solution of lead nitrate (339-359°C). 

There is an account of an incident involving combustion/explosion in the free space of a weak ammonia liquor tank where detailed examination revealed no evidence for an ignition source [5]. The existence of ammonia—air mixtures able to bum only in sufficiently large enclosed volumes was established [6], Previous data on flammability has been summarised and extended by determination of flammability characteristics of ammonia admixed with dry air and oxygen-deficient air at temperatures from ambient up to 400°C. Similar work with added water vapour at 80°C shows that aqueous solutions of below 5% ammonia content do not produce flammable vapours at any temperature, and that above 49°C no flammable vapours are produced by ammonia solution of any concentration. Some data on ignition energy and explosibility are also given [7], Two US incidents serve as a reminder of the considerable explosive potential of ammonia—air mixtures in confined volumes. An... 

The combustion synthesis technique consists of bringing a saturated aqueous solution of the desired metal salts and a suitable organic fuel to the boil, until the mixture ignites a self-sustaining and rather fast combustion reaction, resulting in a dry, usually crystalline, fine oxide powder. By simple calcination, the metal nitrates can, of course, be decomposed into melt oxides upon heating to or above the phase transformation temperature. 

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