CHEMISTRY. The inspired visionary often puts into a few words the truth that men of science reach only by long and laborious toil ; and when the poet wrote that famous line, " Change and decay in all around I see," he was saying in a poet's way what chemistry is forever saying as a scientific fact.
We put a match to the neatly laid fire in the grate and in a moment smoke curls up and flames burst forth; and as we watch the fire burn we see strange changes taking place. Paper and wood disappear, while the glossy black coal flames up and glows and shrinks till it becomes only dust and cinders. Change and decay have taken place before our eyes, and it is the science of chemistry that tells us how and why those changes occur.
Physics and Chemistry Linked Chemistry is really the science of different kinds of matter and their relation to one another, and it is very closely connected with the science of physics, which explains the forces and forms of energy. In fact no one can say where chemistry ends and physics begins, and the great discoveries about atoms and molecules which have been made of late years on the borderline between the two sciences have given rise to a new linking branch of science which we call physical chemistry.
We take a steel knitting needle and put it into a bottle of vitriol or sulphuric acid and it is eaten away.
That is a fact of chemistry. We take a similar needle and draw a magnet across it several times in one direction and the needle itself becomes a magnet.
That is a fact of physics. We take still another needle and leave it out in the damp all night and in the morning it is covered with rust. That is a fact of both chemistry and physics, for the production of a new substance, rust, is chemistry, and the fact that the rusty needle will not conduct electricity so well as when it was bright is physics.
How the Alchemists Gave Us Chemistry Really chemistry is quite a modern science, but it had its beginnings long ago in the days of the old alchemists. Those chemists of the Middle Ages were interested in only one thing. They sought frantically
for some means of changing the baser or cheaper metals into gold. For centuries they worked vainly at this strange task to the neglect of more important matters.
But later on, in more modern times, famous men like Cavendish, Priestley, and Lavoisier began to study the nature of matter. They divided up various bodies like air and water into more elementary sub stances and gradually a list of elements was compiled —substances which it was supposed could not be split up into anything simpler. Thirty years or so ago the list contained 64 elements such as gold, silver, tin, copper, zinc, iron, carbon, sulphur, hydrogen, oxygen, nitrogen, chlorine, and many rarer sub stances, and it was generally believed that these comprised the whole of the elements. Such substances as radium and helium were not then dreamed of.
Nor were many of the relations between the elements clear.
But in recent years many more elements have been discovered and now there are about 90 known. In 1815 an English physician, William Prout, suggested that all the elements were compounds of one mother substance, hydrogen, but the idea was ridiculed.
The very latest discoveries in chemistry and physics, however, rather point to the fact that Prout's idea of a single basic origin of all matter is more or less correct, in which case the quest of the old alchemists would appear to be not quite so mad as was sup posed, and in the hands of the new chemists may prove successful. It may yet be possible to change the baser metals into gold, but probably nobody will want to do so.
An ignorant person would tell us that the world is composed of soil, rock, and water, surrounded by air.
But the chemist analyzes these substances, and finds of the earth as we know it. The next most abundant element is silicon, which forms nearly a third of the crust, and then come six of the metals in the follow ing order: aluminum, iron, calcium, magnesium, sodium, and potassium.