Chemistry

In 1864 Newlands of London and Lothar Meyer of Germany found that if many of the elements were arranged in order of their atomic weights, certain resemblances in their qualities were noticeable between an element and the eighth from it. This became known as the theory of chemical octaves. In 1869 Mendelef made out a new list, reconsidered the resemblances, and left blanks here and there to be filled in with elements still to be discovered. Now the most striking proof of the theory is that elements have actually been discovered answering the description given them and with the proper atomic weights. In his table the elements, arranged in order of their atomic weights, fall naturally into families. The great significance of this theory is that the elements are not wholly independent, but would seem themselves to be compound, with qualities depending on their atomic weights. The large number of new elements recently discovered all find a more or less satisfactory place in the periodic table.

Another conception that is having great influence is that of the charged atom or "ion." Putting together the observations of a number of chemists, von t’Hoff has announced the law that if a substance is dissolved in a large quantity of the solvent the molecules are so far separated as to act as in a gas. Thus they exert pressure on the interior walls of the receptacle. Exceptions to this rule he showed to take place when the atoms of the molecules are electrically dissociated, that is, become charged atoms or "ions." A solution of potassium nitrate is such a charged solution. If an electric current is sent through it, the minus atoms of potassium are attracted to the plus pole, the plus atoms ofnitrate NO3 are drawn to the minus pole. Both sets of atoms are discharged. They then become free to act on the water of the solution. The potassium combines with the oxygen of the water and liberates hydrogen; the NO3 groups combine with the hydrogen of the water and liberate oxygen. This is in general the best explanation of the method of electrolysis.

Doctor Jaques Loeb has shown that such charged salt atoms cause muscular vibrations. A heart will begin beating if placed in such a solution. The electric charge contained by such atoms in solution seems to be enormous. Their influence on life is still a question of study. Dr. Loeb thinks he has been able to start a growth in the unfertilized eggs of sea urchins. It may be, however, that a cross is not always needed between such eggs. Some poisons are shown to contain strong minus ions. Food may even be needed more for its ions than the heat it contains. It is conceivable that a nerve impulse is based on the same principle. The nerves consist of phosphorized fat in a weak salt solution. They are "colloid" substances, that is, they do not crystallize when they solidify. The nerve impulse may be some sort of precipitation along the nerve, each colloid releasing some minus charged ions which precipitate the next colloid. The last minus ions act on and contract the muscle. But this is still in the domain of unproved theory.

Equally unproved is Lord Kelvin’s theory that the atom is a whirling ring in the ether, comparable to a ring of smoke in the air. Such a ring would account for many qualities of the atoms, such as indestructibility, but, as Lord Kelvin himself has said, the hypothesis is as yet only a dream.