as ended
in the conclusion that the sulpho-carbonates are a complete antidote to
these destructive insects. This result has already been announced in
this Miscellany, and it only remains to explain the action of these
salts. Under the influence of carbonic acid, which is always present in
soils containing organic substances, they decompose. A carbonate is
formed, and sulphuretted hydrogen and bisulphide of carbon are evolved.
Both of these are deadly poisons to the phylloxera as well as to man.
To complete the fitness of these salts to agricultural uses, the
sulpho-carbonate of potassium has an excellent effect upon the vines,
potash being one of the most valued constituents of manures. Success in
using the antidote depends upon bringing it in contact with every part
of the root-system of the plant. This can be done by dissolving the
salt, but it is better to mix it with half its weight of lime and
sprinkle it on the ground at the beginning of the rainy season, which
in France lasts from October to March. M. Mouillefert, who examined
this subject under direction of the Academy, reports that as an
antidote the sulpho-carbonates are a proved success, and nothing now
remains but to educate the vine growers to their proper use. This
subject has peculiar interest to Americans, for the phylloxera is our
evil gift to France. It is matter of common observation, both in animal
and vegetable physiology, that one race or species may live in comfort
with an enemy--be it a disease or a parasite--which is destructive to
other species. The American vineyards are by no means free from the
phylloxera. On the contrary, they are full of this insect, but the
vines do not lose their hardiness in consequence. They flourish in
spite of their enemy.

THE SUN'S HEAT.

Prof. Langley of the Allegheny observatory has made a direct comparison
between the heat of the sun and that of the flame in the mouth of a
Bessemer steel convertor. Estimates of the sun's temperature probably
vary among themselves more than any other attempts at scientific
knowledge, ranging from 10,000,000 down to 1,500 deg. We have already
published in this Miscellany some late French determinations which
place it below 2,000 deg. C. Prof. Langley's choice of a standard is
excellent. The flame of the Bessemer convertor results from the burning
of carbon, silicon, iron, and manganese within the vessels, the result
of using this once novel fuel being a heat so great tha