And so, in due season, comes hydrogen, carefully contemplated in my reading, seen and reseen with the eye of the mind before being seen with the eyes of the body. I delight my little rascals by making the hydrogen flame sing in a glass tube, which trickles with the drops of water resulting from the combustion; I make them jump with the explosions of the thunderous mixture.

A log of wood which is composed chiefly of carbon and hydrogen in an unstable union lying upon the ground will gradually decay, as we term it that is, its elements will separate from each other, and form new unions with the elements of the surrounding air, thus returning to their normal condition.

The atmosphere was certainly combustible when it met ours, which makes it impossible for me to believe that their air contained any noticeable amount of oxygen, for anything above twenty per cent oxygen and the rest hydrogen would be violently explosive. Apparently the gas had to mix liberally with our air to reach that proportion.

"By all means," said Mr. Furlong. Mr. Fyshe poured out a wineglassful of soda and handed it to the rector to drink. "Now tell me very truthfully," he said, "is there too much carbon in it?" "By no means," said Mr. Furlong. "And quite frankly not too much hydrogen?" "Oh, decidedly not." "And you would not say that the percentage of sodium bicarbonate was too great for the ordinary taste?"

One sees at a glance that these substances agree in having twice as many hydrogen atoms as there are oxygen atoms, the same proportion that the hydrogen bears to the oxygen in the compound water, a characteristic which makes it easy to remember the general constitution of carbohydrate as compared with the protein.

The absence of sulphureted hydrogen in samples of unfiltered effluent, which have been kept for about six weeks in stoppered bottles, is also a fact of importance. The settled sewage was not in this condition, as it rapidly underwent putrefaction, even in contact with air, in two or three days.

Here we must make a slight digression and speak of the invention of the hydrogen, or gas, balloon. In a previous chapter we read of the discovery of hydrogen gas by Henry Cavendish, and the subsequent experiments with this gas by Dr. Black, of Glasgow.

The food of animals, on the other hand, consists always of organized forms. There is no artificial process by which oxygen, carbon, and hydrogen can be brought into a form suitable for the nourishment of animals. As oxygen, carbon, and hydrogen, they are not food, will not sustain our life, and human art cannot imitate their nutritious combinations.

The Peruvian borax sometimes contains nitre. For testing the purity of refined borax the following simple tests will usually suffice. On passing sulphuretted hydrogen into the solution, no coloration or precipitate should be produced. Calcium Salts. The solution should not give a precipitate with ammonium oxalate solution. Carbonates.

Supposing I now take a glass and put it upside-down over the end of the tube, because the hydrogen is light I expect that it will remain in that vessel a little while. We will now test the contents of our glass to see if there be hydrogen in it. I will now apply a light to the top of the tube. There is the hydrogen burning. There is our philosophical candle.