On examination it was found that the body of the projector was divided internally into two compartments which could be connected by opening another tap. The upper compartment was the compressor and the lower the oil reservoir. The compressor chamber was filled to a pressure of twenty-three atmospheres with deoxygenated air or nitrogen. Air itself cannot be used because of its oxygen content forming an explosive mixture with the vapours from the oil, and any heating on compression, or back-flash from the flame or fuse, might make things very unpleasant for the operator. The nitrogen required for the flame projectors is carried into the field in large cylinders about 4 feet 6 inches in length and 6 inches in diameter. Several of these cylinders have been captured from the enemy since. These cylinders are actually taken into the trenches and the flame projectors charged from them there. The combustible liquid used in the flame throwers has varied in source and composition from time to time, but it invariably has one characteristic which appears to be essential for good results--it must have light or easily volatile and heavy and less volatile fractions mixed in carefully graded proportions. The heavy oil has sometimes been a petroleum product and sometimes a tarry residual oil from the distillation of wood. The light portion, which insures the jet’s keeping alight was originally a light gasolene, but at one period, whether from shortage of petrol or not I do not know, the place of the latter in the mixture was taken by ordinary commercial ether. The lighting device, fixed at the end of the flexible hose, is the most ingenious part of the whole contrivance and is so made that the oil ignites spontaneously the minute the jet is turned on, and is kept alight by a fiercely burning mixture which lasts throughout the discharge. The nozzle is about 9 inches long and detachable so that replacement is easy. It clips into the end of the tube and is held in position by an annular ring. When the oil with its twenty-three atmospheres pressure behind it is rushed out of the jet, it forces up the plunger of a friction lighter and ignites a core of a fierce burning fuse mixture which fills the whole of the space between the central tube and an outer casing. The latter consists of a thick wick soaked in paraffin wax and fitting loosely into a thin brass case. When the nozzle is in position all that is necessary is to turn on the tap, and the stream of flame issues from the tube and can be directed at will. The official name for this instrument we discovered was the “_Flammenwerfer_” (flame thrower) and it is now never known in the British army by anything else than its German name. Indeed this is one of the very few German words we have adopted as an outcome of the war, the only others I can remember being “_strafe_” and “_Kamerad_.”