The water resulting from this detonation was so small in quantity, and in such a state of minute division, as to be invisible. But water certainly was produced; for oxygen is incapable of combining with hydrogen in any other proportions than those that form water; therefore water must always be the result of their combination. If, instead of bringing the hydrogen gas into sudden contact with the atmosphere (as we did just now) so as to make the whole of it explode the moment it is kindled, we allow but a very small surface of gas to burn in contact with the atmosphere, the combustion goes on quietly and gradually at the point of contact, without any detonation, because the surfaces brought together are too small for the immediate union of gases. The experiment is a very easy one. This phial, with a narrow neck, (PLATE VIII. fig. 5.) is full of hydrogen gas, and is carefully corked. If I take out the cork without moving the phial, and quickly approach the candle to the orifice, you will see how different the result will be---- EMILY. How prettily it burns, with a blue flame! The flame is gradually sinking within the phial--now it has entirely disappeared. But does not this combustion likewise produce water? MRS. B. Undoubtedly. In order to make the formation of the water sensible to you, I shall procure a fresh supply of hydrogen gas, by putting into this bottle (PLATE VIII. fig. 6.) iron filings, water, and sulphuric acid, materials similar to those which we have just used for the same purpose. I shall then cork up the bottle, leaving only a small orifice in the cork, with a piece of glass-tube fixed to it, through which the gas will issue in a continued rapid stream. CAROLINE. I hear already the hissing of the gas through the tube, and I can feel a strong current against my hand. MRS. B. This current I am going to kindle with the candle--see how vividly it burns---- EMILY. It burns like a candle with a long flame. But why does this combustion last so much longer than in the former experiment? MRS. B. The combustion goes on uninterruptedly as long as the new gas continues to be produced. Now if I invert this receiver over the flame, you will soon perceive its internal surface covered with a very fine dew, which is pure water---- CAROLINE. Yes, indeed; the glass is now quite dim with moisture! How glad I am that we can see the water produced by this combustion. EMILY. It is exactly what I was anxious to see; for I confess I was a little incredulous. MRS. B. If I had not held the glass-bell over the flame, the water would have escaped in the state of vapour, as it did in the former experiment. We have here, of course, obtained but a very small quantity of water; but the difficulty of procuring a proper apparatus, with sufficient quantities of gases, prevents my showing it you on a larger scale.