Abstract: Air from an air source A, which may be the bleed air of an aircraft, enters the system under the control of an air flow control unit (10). An organic fuel from a fuel reservoir (12 or 13) enters a mixing chamber (16) under the control of fuel flow control unit (14) for mixture with the air. At a first stage the organic fuel is a oxygenated organic fuel from reservoir (12), and at a subsequent stage the organic fuel is a hydrocarbon fuel from reservoir (13). The air and fuel mixture passes to a catalyst bed (18) containing a noble metal catalyst such as platinum, palladium or a mixture thereof. A relatively low temperature, non-flaming reaction occurs and the resultant gas mixture contains a low concentration of oxygen and larger qualities of inert gases such as nitrogen, carbon dioxide and water vapour.

Abstract: According to the invention physiological cooling activity is imparted to tobacco and tobacco-containing manufactures, e.g. pipe tobacco and cigarettes by incorporating therein certain cold receptor stimulating p-menthane-3-carboxamides.