CHAPTER IV.
49. _What is hydrogen?_
Hydrogen is an elementary gas, and is the lightest of all known bodies.
50. _Will hydrogen support animal life?_
It will not. It proves speedily fatal to animals.
51. _Will hydrogen support combustion?_
Although it will burn, yielding a feeble bluish light, it will, if pure, extinguish a flame that may be immersed in it. Hydrogen will therefore _burn_, but will not _support combustion_.
52. _Why will hydrogen explode, if it will not support combustion?_
When hydrogen explodes it is always in combination with _oxygen_, or with the common air, which contains _oxygen_. _Two_ measures of hydrogen and _one_ of oxygen form a most explosive compound.
[Verse: "As smoke is driven away, so drive them away: as wax melteth before the fire, so let the wicked perish at the presence of God."--PSALM XLVI.]
53. _Why does hydrogen explode, when mixed with oxygen, upon being brought in contact with fire?_
Because of its strong affinity for _oxygen_, with which, upon the application of heat, it unites to form water.
54. _Where does hydrogen chiefly exist?_
In the form of _water_, where it exists in combination with _oxygen_. _Eleven_ parts of hydrogen, and _eighty-nine_ of oxygen, form water.
55. _Is hydrogen found elsewhere?_
It is never found but in a state of combination; united with oxygen, it exists in _water_; with nitrogen, in _ammonia_; with chlorine, in _hydro-chloric acid_; with fluorine, in _hydro-fluoric acid_; and in numerous other combinations.
56. _Is the gas used to illuminate our streets, hydrogen gas?_
It is; but it is combined with carbon, derived from the coals from which it is made. It is therefore called _carburetted hydrogen_, which means _hydrogen_ with _carbon_.
57. _How is hydrogen gas obtained from coals?_
It is driven out of the coals by heat, in closed vessels, which prevent its union with _oxygen_.
58. _What becomes of the water which is formed by the burning of hydrogen in oxygen?_
It passes into the air in the form of watery vapour. Frequently it condenses, and may be seen upon the walls and windows of rooms where many lights or fires are burning. Sometimes, also, portions of it become condensed in the globes of the glasses that are suspended over the jets of gas. _A large volume of these gases forms only a very small volume of water._
59. _What becomes of the carbonic acid gas which is produced by combustion?_
It is diffused in the air, which should be removed by adequate ventilation.
[Verse: "I will both lay me down in peace and sleep: for thou, Lord, only, makest me dwell in safety."--PSALM IV.]
60. _What proportion of carbonic acid gas is dangerous to life?_
Any proportion over the natural one of 1 per cent. may be regarded as _injurious_. But toxicologists state that _five per cent._ of carbonic acid gas in the atmosphere is _dangerous_ to life.
61. _What are toxicologists?_
Persons who study the nature and effects of poisons and their antidotes.
62. _Which kind of combustible used for lighting tends most to vitiate the air?_
Assuming all the lights to be of the same intensity, the degree in which the substances burnt would vitiate the atmosphere may be gathered from the number of minutes each would take to exhaust a given quantity of air. This has been found to be: rape oil, 71 minutes; olive oil, 72; Russian tallow, 75; town tallow, 76; sperm oil, 76; stearic acid, 77; wax candles, 79; spermaceti candles, 83; common coal gas, 98; canal coal gas, 152. Thus it is shown that rape oil is _most destructive_ of the atmosphere, and that coal gas is the _least destructive_.
63. _Is an escape of hydrogen gas from a gas-pipe dangerous to life?_
It is dangerous, first, by _inhalation_. There are no less than six deaths upon record of persons who were killed by sleeping in rooms near to which there was a leakage of gas.
It is dangerous, secondly, by _explosion_.
In 1848, an explosion of gas occurred in Albany-street, Regent's-park, London. The gas accumulated in a shop for a very short time only. It had been escaping from a crack in the meter for about one hour and twenty minutes. The area of the room was about 1,620 cubic feet. When the gas exploded, it blew out the entire front of the premises, carried two persons through a window into an adjoining yard, and forced another person on to the pavement on the opposite side of the street, where she was killed. The effect of the explosion was felt for more than a quarter of a mile on each side of the house, and most of the windows in the neighbourhood were shattered. The iron railings over the area of the house directly opposite were snapped asunder; and a part of the roof, and the back windows of another house, were carried to a distance of from 200 to 300 yards. The pavement was torn up for a considerable length, and the damage done to 103 houses was afterwards reported to amount to £20,000. Other serious explosions have taken place. The explosions of "_coal damp_," which frequently occur in mines, are of a similar character.
[Verse: "O Lord, our Lord, how excellent is thy name in all the earth! who hast set thy glory above the heavens."--PSALM VIII.]
64. _What proportion of hydrogen gas with atmospheric air will explode?_
According to the researches of Sir Humphrey Davy, _seven_ or _eight_ parts of _air_, to _one_ of _gas_, produce the greatest explosive effect; while _larger_ proportions of gas are less dangerous. A mixture of _equal parts_ of gas and air will burn, but it will not explode. The same is the case with a mixture of _two_ of _air_, or _three_ of _air_, and _one_ of _gas_; but _four_ of _air_ and _one_ of _gas_ begin to be explosive, and the explosive tendency increases up to _seven_ or _eight_ of _air_ and _one_ of _gas_, after which the increased proportion of gas diminishes the force of the explosion.
65. _What is the best method of preventing the explosion of gas?_
Observe the rule, _never to approach a supposed leakage with a light_. Fortunately the gas, which threatens our lives, warns us of the danger by its pungent smell. The first thing to be done is to open windows and doors, and to ventilate the apartment. Then turn the gas off at the main, and wait a short time until the accumulated gas has been dispersed.
66. _Does hydrogen gas rise or fall when it escapes?_
Being _twelve times lighter than common air_ it _rises_, and therefore it would be better for ventilation to open the window at the _top_ than at the _bottom_. But all gases exhibit a strong tendency to _diffuse themselves_, and therefore they do not rise or fall in the degree that might be anticipated.
67. _What proportion of hydrogen in the air is dangerous to life, if inhaled?_
One-fiftieth part has been found to have a _serious effect_ upon animals. The effects it produces upon the human system are those of depression, headache, sickness, and general prostration of the vital powers. It is therefore advisable to observe precautions in the use of gas.
[Verse: "From the place of his habitation he looketh upon all the inhabitants of the earth."--PSALM XXXIII.]
68. _What proportion of gas in the air may be recognised by the smell?_
By persons of acute powers of smelling it may be recognised when there is _one_ part of _gas_ in _five hundred parts of atmospheric air_; but it becomes very perceptible when it forms _one_ part in _a hundred and fifty_. Warning is, therefore, given to us long before the point of danger arrives.
69. _What other sources of hydrogen are there in our dwellings?_
It arises from the decomposition of animal and vegetable substances, containing _sulphur_ and _hydrogen_. These give off a gas called _sulphuretted hydrogen_, from which the fætid effluviam of drains and water-closets chiefly arise. We should, therefore, take every precaution to secure effective drainage, and to keep drain-traps in proper order.
70. _May the use of gas for purposes of illumination be considered highly dangerous?_
Not if it is intelligently managed. The appliances for the regulation of gas are so very simple and perfect, that accidents seldom arise except from neglect. In England 6,000,000 tons of coal are usually consumed in the manufacture of gas, producing 60,000,000,000 cubic feet of gas. And yet accidents are of very uncommon occurrence.