The Romance of Modern Chemistry

NATURE’S BUILDING MATERIAL Apart from the thorough-going change of properties which accompanies the combination of two elements, chemists have discovered some very remarkable facts bearing on the proportions by weight in which combina- tion takes place. Elements are exceedingly particular as to how far they give themselves away, and nothing will persuade them to go more than a certain distance in meeting the advances of other elements. When iron and sulphur combine, they do so in the proportion of seven parts of iron to four parts of sulphur. If a mixture of eight ounces of iron with four ounces of sulphur were heated, nothing would induce that extra ounce of iron to give up its independence and enter the compound. And similarly if we took a mixture of seven ounces of iron with five ounces of sulphur, the extra ounce of sulphur would absolutely refuse to be anything else than sulphur. So that elements combine in perfectly definite proportions. However or wherever a compound is pro- duced, in the laboratory of the chemist or in the laboratory of Nature, it invariably consists of the same elements united in exactly the same proportions. There are cases, indeed, in which two elements unite to form more than one compound. Thus there are two oxides of copper, one containing eight parts by weight of copper to two parts by weight of oxygen, and another containing eight parts of copper to one of oxygen. Observe that the amount of oxygen uniting with eight parts of copper must be either one or two ; no compound can be formed containing between one and two parts of oxygen to eight parts of copper. And this is merely an example of what is always found to be the case. When one element combines with another element to foim nioie than one compound, the amounts of the second element