Let us make use of an electric current to decompose water into its elements, hydrogen and oxygen. I have a three-ounce wide-mouthed bottle (Fig. 153) and through its cork I pass two short pieces of No. 24 platinum wire by pushing a stout needle through first. I fill this bottle with pure water and cut a slight furrow in the side of the cork, where water may drip out when the gas is produced in the bottle. We crowd the cork firmly into the mouth of the bottle and invert it. No water drops out. We bend the ends of the platinum wires into hooks and hang upon them the wires bringing the dynamo direct current. There is no evidence of chemical action. Pure water is an exceedingly poor conductor of electricity. Let us now put about fifty-five ohms of resistance into the dynamo circuit, so that it will pass about two amperes, and put a very small pinch of salt into the water, which makes it so good a conductor that its resistance may be ignored. When now we close the circuit, as before, a brisk effervescence takes place. Bubbles of gas rapidly form on the platinum wires and break away, rising through the liquid. Twice as many form on the negative wire as on the positive one. As these gases rise to the top of the bottle an equal volume of the water drips out through the small hole in the cork. [Illustration: Fig. 153] Two amperes of electricity will liberate two fluid ounces of hydrogen at the negative pole and one fluid ounce of oxygen at the positive pole, in five minutes. Hence in five minutes the bottle should be full of a mixture of two gases, two thirds of which, by volume, is hydrogen and one third oxygen. We will catch the water which drips out so that we may measure it. The bottle being now full of gas I shut off the current, and removing the cork I bring a flame to its mouth. A very loud and startling explosion takes place. We pour the water back into the bottle, and it seems to fill it as well as before. We have decomposed a few drops of water--not enough to measure--into two gases, one of which, the hydrogen, occupied two thirds of the bottle, and the other, oxygen, occupied the remaining third. At ordinary temperatures they would not reunite, but when raised to their kindling temperature they united, producing light, heat, a loud noise, and the few drops of water which had been originally decomposed by the current. This is the electrolysis of water. I wonder if any such chemical action took place in Ernest's body when he received that severe shock on the motor boat the other day.