nce, was heartily applauded.

The president, in his inaugural address, said Manchester, distinguished
as the birthplace of two of the greatest discoveries of modern science,
welcomed the visit of the British Association for the third time. Those
discoveries were the atomic theory of which John Dalton was the author,
and the most far-reaching scientific principle of modern times, namely,
that of the conservation of energy, which was given to the world about
the year 1842 by Dr. Joule. While the place suggested these reminders,
the time, the year of the Queen's jubilee, excited a feeling of
thankfulness that they had lived in an age which had witnessed an
advance in our knowledge of nature and a consequent improvement in the
physical, moral, and intellectual well-being of the people hitherto
unknown.

PROGRESS OF CHEMISTRY.

A sketch of that progress in the science of chemistry alone would be
the subject of his address. The initial point was the views of Dalton
and his contemporaries compared with the ideas which now prevail; and
he (the president) examined this comparison by the light which the
research of the last fifty years had thrown on the subject of the
Daltonian atoms, in the three-fold aspect of their size,
indivisibility, and mutual relationships, and their motions.

SIZE OF THE ATOM.

As to the size of the atom, Loschmidt, of Vienna, had come to the
conclusion that the diameter of an atom of oxygen or nitrogen was the
ten-millionth part of a centimeter. With the highest known magnifying
power we could distinguish the forty-thousandth part of a centimeter.
If, now, we imagine a cubic box each of whose sides had this length,
such a box, when filled with air, would contain from sixty to a
hundred millions of atoms of oxygen and nitrogen. As to the
indivisibility of the atom, the space of fifty years had completely
changed the face of the inquiry. Not only had the number of distinct,
well-established elementary bodies increased from fifty-three in 1837
to seventy in 1887, but the properties of these elements had been
studied, and were now known with a degree of precision then undreamt
of. Had the atoms of our present elements been made to yield? To this
a negative answer must undoubtedly be given, for even the highest of
terrestrial temperatures, that of the electric spark, had failed to
shake any one of these atoms in two. This was shown by the results
with which spectrum analysis had enriched our knowle