exercise an important influence on the development of a truer chemistry. Such is always the case in natural science: from the labors of a large number of comparatively obscure observers, we become able to deduce the expression of a natural law, or the true explanation of a class of phenomena.
"As true chemistry advanced, alchemy gradually disappeared, and its followers diminished in numbers, until finally the transmutation of the metals was believed only by the ignorant. But the science of chemistry is a progressive one, and has been and is constantly changing; the views of the chemical constitution of substances held by the best chemists have undergone numerous alterations; and now, long after the time of the alchemists, chemists are beginning to hold opinions in a certain degree resembling the old alchemical notions; or, to speak more definitely, we can see that the distinction between the so-called elementary or simple substances may not be as wide as we have been wont to regard it, and that we may, some time, discover the causes of the differences between them. In the present article, it is our intention to briefly mention some of the arguments which seem to lead us in this direction.
"Between the alchemical opinions and those of the present day we notice at once a great distinction. The alchemists knew nothing of the elements, as we style them; neither had they any conception of the constitution of salts. At the present time we are acquainted with sixty-five elements; that is to say, there are sixty-five bodies that we cannot now show to be compounds. It is important to notice that the difference between two elements is often very slight. For instance, the distinction between nickel and cobalt is by no means a marked one; they always occur together, and have many common properties. Now we know that a very minute quantity of extraneous matter will often entirely change the properties or mark the reactions of many substances. We have a familiar and striking illustration of this in iron; a very little sulphur or phosphorus is able to seriously injure the quality of a very large amount of metal. The difference between the various kinds of iron (cast and malleable iron, steel, etc.) is caused by the abstraction or addition of small quantities of carbon; indeed, perfectly pure metallic iron in any quantity has never been made. Iron is itself closely allied to cobalt and nickel; they
