CHAPTER I.
A SLIGHT TEST OF THE IMAGINATION.
We live in a world in which certain conditions of the atmosphere and the so-called elements surrounding our daily existence, are entirely familiar to us. From force of habit we are likely to forget that had Nature, for instance, been planned under a different range of livable temperatures, all the familiar objects of our daily existence would have existed under entirely different form.
For instance, if the normal temperature had been about 2700 degrees Fahrenheit instead of about 60 degrees Fahrenheit, and we had been constructed so that we could comfortably endure that degree of temperature, we could have gone sailing on a sea of molten iron, in boats built of plumbago crucibles, and oars made of silica brick. Under these delightful conditions we could place frozen lumps of our sea of iron in our ice boxes for refrigeration. Flat irons and stove lids would therefore have been the product of the ice man. The water with which we are now familiar, of course, could not exist in its liquid form, or even as steam, but instead as a highly gaseous state, which we would probably have been called upon to breathe. Certain other substances with which we are perfectly familiar in our daily life, such as the common stick sulphur, for instance, would exist in an entirely different physical state, although their chemical properties would be entirely unchanged, and we would be given to understand that an "allotropic" transformation had taken place.
If we can now imagine ourselves as existing under the relative conditions described above, which are undoubtedly the "natural" conditions of some other world, it will then be easy for us to understand quite clearly some of the other "allotropic" forms of iron and steel than those with which we are at present familiar.
CHAPTER II.
COMPARISON BETWEEN CONDITIONS WHICH
EXIST IN THE IRON AND STEEL FAMILY
TO THOSE WHICH EXIST WITH
MORE FAMILIAR ELEMENTS.
One of the first physical changes which we would discover would be that when we desired to "freeze" a "crucible" pailful of our iron water, we could do so much more easily if the same were in its absolutely pure state than we could if it were mixed with some other element, such as carbon. Of course, we have long known that this is the case with water and salt, and just as it becomes harder and harder to freeze water with greater and greater percentages of salt mixed with it, so the freezing of iron with greater and greater percentages of carbon mixed with it, would also occur at lower and lower temperatures.
If we started to add salt to a pail of water we, of course, would have different degrees of brine. Just so with the addition of carbon to a crucible of pure iron, we would likewise have different degrees of the resulting mixture. In adding the salt to the pailful of water, we would arrive at a point where the water had absorbed all of the salt which it was capable of holding at room temperature. If we had added a little less salt we would have had free water in excess of salt, and if we had added a little more salt it would have been impossible for the water to have dissolved it, and we would, therefore, have had salt in excess of water.
For convenience we will call the mixture above mentioned, at which the water had become thoroughly saturated with the salt, "cementite", because this is the name which our friends, the metallurgists, have given to a similar mixture of iron and carbon. They call the water, "ferrite"; the salt, "carbide" and the resulting mixture of brine, "cementite". This mixture of iron and carbon always exists in exactly the same ratio, namely, 93.4% iron and 6.6% carbon, and is expressed chemically by the symbol Fe3C, which means, in other words, that three "atoms" of iron have united with one "atom" of carbon to form the "chemical compound", "iron carbide", which the metallurgists, as above mentioned, desire to term "Cementite".