So far the story is absolutely commonplace. But now the greenish powder comes upon the scene. The source of that greenish powder seems, unfortunately, lost. Master Whibble tells a tortuous story of finding it done up in a packet in a disused limekiln near the Downs. It would have been an excellent thing for Plattner, and possibly for Master Whibble's family, if a match could have been applied to that powder there and then. The young gentleman certainly did not bring it to school in a packet, but in a common eight-ounce graduated medicine bottle, plugged with masticated newspaper. He gave it to Plattner at the end of the afternoon school. Four boys had been detained after school prayers in order to complete some neglected tasks, and Plattner was supervising these in the small class-room in which the chemical teaching was conducted. The appliances for the practical teaching of chemistry in the Sussexville Proprietary School, as in most small schools in this country, are characterised by a severe simplicity. They are kept in a small cupboard standing in a recess, and having about the same capacity as a common travelling trunk. Plattner, being bored with his passive superintendence, seems to have welcomed the intervention of Whibble with his green powder as an agreeable diversion, and, unlocking this cupboard, proceeded at once with his analytical experiments. Whibble sat, luckily for himself, at a safe distance, regarding him. The four malefactors, feigning a profound absorption in their work, watched him furtively with the keenest interest. For even within the limits of the Three Gases, Plattner's practical chemistry was, I understand, temerarious. They are practically unanimous in their account of Plattner's proceedings. He poured a little of the green powder into a test-tube, and tried the substance with water, hydrochloric acid, nitric acid, and sulphuric acid in succession. Getting no result, he emptied out a little heap--nearly half the bottleful, in fact--upon a slate and tried a match. He held the medicine bottle in his left hand. The stuff began to smoke and melt, and then exploded with deafening violence and a blinding flash.