called forth is akin to that called forth by any clever trickster. It is unfortunate that experiments, originally devised for the purpose of teaching facts, should have come to be employed simply for the sake of their æsthetic effects. There can certainly be no harm in making an experiment a thing of beauty, so long as its real object is not by this means interfered with; indeed, this may be advisable, in order more strongly to impress upon the minds of the hearers the facts which are to be taught, but the tendency is very strong toward the condition above described: the science is made to serve the purposes of showmen, and the rabble shout the more, the greater the display. Those who serve up this class of lectures are doing positive harm by belittling the science whose name they profane; and they are also doing negative harm by failing to make use of the opportunities afforded them to draw the minds of men upward to higher conceptions, and thus of elevating mankind. They neither recognize the science nor the art of chemistry, but by their actions teach that it is a pastime of no particular value.
In the foregoing we have drawn a line between the science and the art of chemistry. The character of the art is perfectly plain to every one. He who analyzes substances in order to decide questions solely of practical importance; who examines the properties of substances solely with a view of determining the practical uses to which these substances can be put; whose only problem relates to the applications of the truths of chemistry to the uses of man—he practises the art of chemistry.
But it is time to inquire what the science is, and what its relation to the art is. A science is a collection of principles, well established, applying to a certain class of phenomena. The science, of chemistry is that particular science which treats of the action of bodies upon each other, in so far as this action causes a change in the composition of the bodies. All the so-called natural laws which govern this kind of action belong legitimately to the field of chemistry. The science is, strictly speaking, a part of that broader science which treats of the action of matter upon matter, viz., physics; but it is usual to consider the two as separate sciences. Its first object is to determine the laws of combination and decomposition of bodies, and its state of perfection will be reached when so much is known concerning these laws that we shall be able in every case to foretell what changes will ensue when two or more bodies are brought together, or when certain influences are brought to bear upon a body. We are so very far from this perfect state at present that we cannot even say what kind of reasoning processes will be necessary to enable us to draw the proper conclusions from given facts. It appears probable, however, that chemistry will gradually develop into a true mathematical science, and that, having reached this state, chemists will determine the orbits of atoms, their rates of motion, their perturbations by methods similar