CHAPTER VI.
CHEMISTRY, MEDICINES, SURGERY, DENTISTRY
Chemistry, having for its field the properties and changes of matter, has excited more or less attention ever since men had the power to observe, to think, and to experiment.
Some knowledge of chemistry must have existed among the ancients to have enabled the Egyptians to smelt ores and work metals, to dye their cloths, to make glass, and to preserve their dead from decomposition; so, too, to this extent among the Phœnicians, the Israelites, the Greeks and the Romans; and perhaps to a greater extent among the Chinese, who added powder to the above named and other chemical products. Aristotle speculated, and the alchemists of the middle ages busied themselves in magic and guess-work. It reached the dignity of a science in the seventeenth and eighteenth centuries, by the labours of such men, in the former century, as Libavius, Van Helmont, Glauber, Tachenius, Boyle, Lémery and Becher; Stahl, Boerhaave and Hamberg in both; and of Black, Cavendish, Lavoisier, Priestley and others in the eighteenth.
But so great have been the discoveries and inventions in this science during the nineteenth century that any chemist of any previous age, if permitted to look forward upon them, would have felt
"Like some watcher of the skies
When a new planet swims into his ken."
Indeed, the chemistry of this century is a new world, of which all the previous discoveries in that line were but floating nebulæ.
So vast and astonishingly fast has been the growth and development of this science that before the century was two-thirds through its course Watts published his Dictionary of Chemistry in five volumes, averaging a thousand closely printed pages, followed soon by a thousand-page supplement; and it would have required such a volume every year since to adequately report the progress of the science. Nomenclatures, formulas, apparatuses and processes have all changed. It was deemed necessary to publish works on The New Chemistry, and Professor J. P. Cooke is the author of an admirable volume under that title.
We can, therefore, in this chapter only step from one to another of some of the peaks that rise above the vast surrounding country, and note some of the lesser objects as they appear in the vales below.
The leading discoveries of the century which have done so much to aid Chemistry in its giant strides are the atomic and molecular theories, the mechanics of light, heat, and electricity, the correlation and conservation of forces, their invariable quantity, and their indestructibility, spectrum analysis and the laws of chemical changes.
John Dalton, that humble child of English north-country Quaker stock, self-taught and a teacher all his life, in 1803 gave to the world his atomic theory of chemistry, whereby the existence of matter in ultimate atoms was removed from the region of the speculation of certain ancient philosophers, and established on a sure foundation.
The question asked and answered by Dalton was, what is the relative weight of the atoms composing the elementary bodies?
He discovered that one chemical element or compound can combine with another chemical element, to form a new compound, in two different proportions by weight, which stand to each other in the simple ratio of one to two; and at the same time he published a table of the Relative weight of the ultimate particles of Gaseous and other Bodies. Although the details of this table have since been changed, the principles of his discovery remain unchanged. Says Professor Roscoe:
"Chemistry could hardly be said to exist as a science before the establishment of the laws of combination in multiple proportions, and the subsequent progress of chemical science materially depended upon the determination of these combined proportions or atomic weights of the elements first set up by Dalton. So that among the founders of our science, next to the name of the great French Philosopher, Lavoisier, will stand in future ages the name of John Dalton, of Manchester."
Less conspicuous but still eminently useful were his discoveries and labours in other directions, in the expansion of gases, evaporation, steam, etc.
Wollaston and Gay-Lussac, both great chemists, applied Dalton's discovery to wide and most important fields in the chemical arts.
Also contemporaneous with Dalton was the great German chemist, Berzelius, who confirmed and extended the discoveries of Dalton. More than this, it has been said of Berzelius:
"In him were united all the different impulses which have advanced the science since the beginning of the present epoch. The fruit of his labors is scattered throughout the entire domain of the science. Hardly a substance exists to the knowledge of which he has not in some way contributed. A direct descendant of the school of his countryman, Bergman, he was especially renowned as an analyst. No chemist has determined by direct experiment the composition of a greater number of substances. No one has exerted a greater influence in extending the field of analytical chemistry."
As to light, the great Huygens, the astronomer and mathematician, the improver of differential calculus and of telescopes, the inventor of the pendulum clock, chronometers, and the balance wheel to the watch, and discoverer of the laws of the double refraction of light and of polarisation, had in the 17th century clearly advanced the idea that light was propagated from luminous bodies, not as a stream of particles through the air but in waves or vibrations of ether, which is a universal medium extending through all space and into all bodies. This fundamental principle now enters into the explanation of all the phenomena of light.
Newton in the next century, with the prism, decomposed light, and in a darkened chamber reproduced all the colours and tints of the rainbow. But there were dark lines in that beam of broken sunlight which Newton did not notice.
It was left to Joseph von Fraunhofer, a German optician, and to the 19th century, and nearly one hundred years after Newton's experiments with the prism, to discover, with finer prisms that he had made, some 590 of these black lines crossing the solar spectrum. What they were he did not know, but conjectured that they were caused by something which existed in the sun and stars and not in our air. But from that time they were called Fraunhofer's dark lines.
From the vantage ground of these developments we are now enabled to step to that mountain peak of discovery from which the sun and stars were looked into, their elements portrayed, their very motions determined, and their brotherhood with the earth, in substance, ascertained.
The great discovery of the cause of Fraunhofer's dark bands in the broken sunlight was made by Gustave Robert Kirchoff, a German physician, in his laboratory in Heidelberg, in 1860, in conjunction with his fellow worker, Robert Bunsen.
Kirchoff happened to let a solar ray pass through a flame coloured with sodium, and through a prism, so that the spectrum of the sun and the flame fell one upon another. It was expected that the well known yellow line of sodium would come out in the solar spectrum, but it was just the opposite that took place. Where the bright yellow line should have fallen appeared a dark line.
With this observation was coupled the reflection that heat passes from a body of a higher temperature to one of a lower, and not inversely. Experiments followed: iron, sodium, copper, etc., were heated to incandescence and their colours prismatically separated. These were transversed with the same colours of other heated bodies, and the latter were absorbed and rendered black. Kirchoff then announced his law that all bodies absorb chiefly those colours which they themselves emit. Therefore these vapours of the sun which were rendered in black lines were so produced by crossing terrestrial vapors of the same nature.
Thus by the prism and the blowpipe were the same substances found in the sun, the stars, and the earth. The elements of every substance submitted to the process were analysed, and many secrets in the universe of matter were revealed.
Young, of America, invented a splendid combination of spectroscope and telescope, and Huggins of England was the first to establish by spectrum analysis the approach and retreat of the stars.
It was prior to this time that those wonderful discoveries and labours were made which developed the true nature of heat, which demonstrated the kinship and correlation of the forces of Nature, their conservation,