Part 16

It is capable of showing electric phenomena when rubbed, giving out slight sparks, and first attracting and then repelling light bodies, such as small pieces of paper, etc. It is so bad a conductor of heat, that if grasped suddenly in a hot hand, it will crack and split into pieces just as glass does when suddenly heated or cooled--of course I am speaking of the roll brimstone. Water has no effect on it, as may be seen in the pans placed for pet dogs to drink out of, where the same piece of brimstone lies for years entirely unaltered, though it is supposed to prevent the dogs from having the mange!

Sulphur is largely used in the arts, principally in the manufacture of gunpowder, and fireworks of various kinds.

It combines with hydrogen and forms a gaseous compound called sulphureted hydrogen, which is almost the most poisonous of all the gases. It fortunately has so abominable a smell that due notice is given of its presence. Rotten eggs, a dirty gun-barrel, cabbage water, putrid animal and vegetable matter, etc., are indebted to this gas for their inviting odor; and it is found in certain mineral springs, as at Harrogate, where the water contains a considerable quantity of this gas, and is found useful in many diseases of the skin. It is also given off in a gaseous form by some volcanoes.

This gas may be obtained by pouring dilute hydrochloric acid upon a metallic sulphuret, such as that called crude antimony, being a native sulphuret of that metal. The gas may be kept for a short time over water. It is colorless and transparent, inflammable, but quite irrespirable, a small bird dying instantly when placed in air containing only 1-1500th of this gas. Its most remarkable property perhaps is the effect it has on certain metallic oxides and other metallic salts, blackening them instantly. White paint is easily stained by this gas, and it will darken the color of a metal in a solution, especially of lead, even when diluted with 20,000 times its weight of water. By way of experiment slips of ribbon, silk, or even paper, may be wetted with various metallic solutions, such as silver, mercury, lead, etc., or words may be written with the solutions, and on holding them over a stream of this gas they will be instantly darkened.

If this gas be collected in the pneumatic trough, which is usually painted white, you will have the pleasure of seeing the color changed to a very dark brown when your experiments are finished. With this very limited description of some of the non-metallic elements and their combinations, we must, for want of space, take leave of this division of chemistry, “the beginning of which is pleasure, its progress knowledge, its objects truth and utility.”

Metals.

We have a few words to say about a class of bodies called metals, which are of the utmost importance to mankind, and indeed without some of them, especially iron, few of the arts of civilized life could exist.

Fifty substances are now included in the list of metals; some of them, however, are only supposed to exist, such as ammonium, the supposed base of ammonia; and very many are to be viewed rather in the light of chemical curiosities, as from their great rarity they are too expensive for use, even if possessed of valuable properties of which others might be destitute.

Several metals have been known from the earliest period of which we have any record; such were iron, gold, silver, copper, lead, tin, mercury, and probably zinc, or at least its ores; for brass, which is an alloy of copper and zinc, is frequently mentioned in the early part of the Old Testament. In the sixteenth century others were discovered, such as antimony and bismuth. In the last century, cobalt, arsenic, platinum, nickel, manganese and chromium, together with several unimportant metals, were discovered by various philosophers; while in the present century, Dr. Wollaston discovered rhodium, the hardest and nearly the most indestructible of all the metals; and a few years later Sir Humphry Davy found that the alkalies, potash and soda, with many of the earths as they were called, had each a metal for its base, to which he gave the Latin name of the alkali or earth, with the termination um, as potassium, the base of potassa, sodium of soda, calcium of calx (lime), etc.

Until Sir H. Davy’s discovery of the metals of the alkalies, great specific gravity was regarded as one of the most striking characteristics of a metal, the lightest of them being much heavier than the heaviest earth; but potassium is very much lighter than water, and not much heavier than spirits of wine. The other metals vary from a specific gravity of nearly twenty-one--or twenty-one times heavier than an equal bulk of water--that of platinum, to somewhat less than seven, which is the specific gravity of antimony.

When pure, they all have a luster, differing indeed among themselves, but so peculiar that it is called the metallic luster; for instance, gold and copper are yellow and red--nearly all the others white, but of a different shade; still there is no mistaking their metallic character, no other substances at all equaling them in this respect. They are also opaque, although some, like gold, when reduced to thin films, allow light to pass through them. They are all good conductors of heat and electricity, though some possess that property to a greater extent than others.

Many of them are what is called malleable, that is, may be extended or spread out by rolling, or beating them with a hammer; and ductile, or have the property of being drawn out into wire. Gold, silver, copper, and iron are the most remarkable in this respect.

All the metals are fusible, but some require very different degrees of heat to render them fluid--platinum requiring the heat of the oxy-hydrogen blowpipe, while tin melts in the flame of a candle, and mercury is fluid at all temperatures in this climate, but becomes solid at 40 degrees Fahrenheit below 0--a temperature occasionally experienced in the Arctic regions, where the mercurial thermometer is useless, the mercury becoming solid.

They are all excellent conductors of heat and electricity, and have the property of reflecting light and forming mirrors; for looking-glasses owe their power of reflecting objects principally to what is called the “silvering;” that is, a mixture of mercury and tin spread over the back of the glass, which being transparent, allows the image reflected from the metal to pass through it.

The following classification is most instructive, because it suggests to the young student that there must be identical properties in the metals thus placed together:

Class 1. Ammonium, cæsium, lithium, potassium, sodium.

Class 2. Calcium, barium, strontium.

Class 3. Aluminium, cerium, didymium, erbium, glucinium, lanthanum, thorium, yttrium, zirconium.

Class 4. Zinc class: cadmium, magnesium, zinc.

Class 5. Iron class: cobalt, chromium, indium, iron, manganese, nickel, uranium.

Class 6. Tin class: niobium, tantalum, tin, titanium.

Class 7. Tungsten class: molybdenum, tungsten, vanadium.

Class 8. Arsenic class: antimony, arsenic, bismuth.

Class 9. Lead class: lead, thallium.

Class 10. Silver class: copper, mercury, silver.

Class 11. Gold class: gold, iridium, osmium, palladium, platinum, rhodium, ruthenium.

Potassium.

Potassium was discovered by Sir H. Davy in the beginning of the present century. It is a brilliant white metal, so soft as to be easily cut with a penknife, and so light as to swim upon water, on which it acts with great energy, uniting with the oxygen, and liberating the hydrogen, which takes fire as it escapes.