In one case a lance containing white and green composition burst into flame on the work bench. This provided an explanation to an explosion at the same factory which had taken place ten days before in a magazine containing between 6,000 and 7,000 lbs. of display fireworks. An occurrence of a similar nature was observed at Brighton in 1903, when some changing coloured lights which had been removed from a building where a fire had taken place (the fireworks not being involved in any way) ignited some days afterwards. It is thought that the lights may have been wetted during the fire, and upon drying out some days later the different compositions in contact in the case or cases set up chemical action, which resulted in spontaneous ignition. It was found on examination that a blue containing sulphur was in contact with a green containing chlorate. It may be noted here that mixtures which are damped during manufacture are more liable to spontaneous ignition than those manipulated in a dry state. Many accidents and explosions are left unexplained, either because the evidence is destroyed by the resulting fire or by the death of the witness or witnesses, or because of the difficulty often experienced in getting the workpeople to give a full and faithful account of what occurred, fearing to cause trouble for themselves or others concerned. There can be no doubt that the cause is frequently carelessness or mistakes on the part of workers. In a large number of cases, however, this explanation gives no help and the cause remains obscure. One such may be mentioned: In 1902 an explosion occurred in a store for non-explosive ingredients, in which were kept the chemicals used in a firework factory. In the building at the time was a workman who appears to have been engaged in sifting chlorate of potash, and the technical manager of the factory who seems to have been weighing out ingredients. There is no doubt that he was a man of very considerable experience, and from his responsible position unlikely either to take risks or be guilty of carelessness. An explosion occurred in the building, killing both occupants, and of so violent a nature as to sever the foot of the manager and to project one of the sheets of corrugated iron with which the roof was covered a distance of thirty yards. No explanation of this occurrence was arrived at other than that in some way some of the chemicals must have become mixed to form a sensitive and violent explosive; so much is obvious, but how the chemicals became so mixed remains a mystery, as no mixing was actually done in the building. The ignition of such a mixture is less obscure as magazine boots were not necessary in the building owing to the non-hazardous nature of the work carried on there, and sufficient friction would be produced to fire even a fairly sensitive mixture between a nailed boot sole and a wood floor.