The diffusion of the solar
rays acting on the 20 inch heater being in the ratio of 1 to 10,241, the
temperature of the solar surface cannot be less than 298.87 deg. x 10,241 =
3,060,727 deg. F. This underrated computation must be accepted unless it can
be shown that the temperature produced by radiant heat is not inversely as
the diffusion of the rays. Physicists who question the existence of such
high solar temperature should bear in mind that in consequence of the
great attraction of the solar mass, hydrogen on the sun's surface raised
to a temperature of 4,000 deg. C. will be nearly twice as heavy as hydrogen on
the surface of the earth at ordinary atmospheric temperatures; and that,
owing to the immense depth of the solar atmosphere, its density would be
so enormous at the stated low temperature that the observed rapid
movements within the solar envelope could not possibly take place. It
scarcely needs demonstration to prove that extreme tenuity can alone
account for the extraordinary velocities recorded by observers of solar
phenomena. But _extreme tenuity_ is incompatible with low temperature and
the pressure produced by an atmospheric column probably exceeding 50,000
miles in height subjected to the sun's powerful attraction, diminished
only one-fourth at the stated elevation. These facts warrant the
conclusion that the high temperature established by our investigation is
requisite to prevent undue density of the solar atmosphere.

It is not intended at present to discuss the necessity of tenuity with
reference to the functions of the sun as a radiator; yet it will be proper
to observe that on merely dynamical grounds the enormous density of the
solar envelope which would result from low temperature presents an
unanswerable objection to the assumption of Pouillet, Vicaire,
Sainte-Claire Deville, and other eminent _savants_, that the temperature
of the solar surface does not reach 3,000 deg. C.

J. ERICSSON.

* * * * *

CHEMICAL NATURE OF STARCH GRAINS.

Dr. Brukner has contributed to the _Proceedings_ of the Vienna Academy of
Sciences a paper on the "Chemical Nature of the Different Varieties of
Starch," especially in reference to the question whether the granulose of
Nageli, the soluble starch of Jessen, the amylodextrin of W. Nageli, and
the amidulin of Nasse are the same or different substances. A single
experiment will serve to show that under certain conditions a so