alumina would be analogous to yttria."--_Nature._

* * * * *




CARBONIC ACID IN THE AIR.

By THOMAS C. VAN NUYS and BENJAMIN F. ADAMS, JR.


During the month of April, 1886, we made eighteen estimations of
carbonic acid in the air, employing Van Nuys' apparatus,[1] recently
described in this journal. These estimations were made in the
University Park, one-half mile from the town of Bloomington. The park
is hilly, thinly shaded, and higher than the surrounding country. The
formation is sub-carboniferous and altitude 228 meters. There are no
lowlands or swamps near. The estimations were made at 10 A.M.

[Footnote 1: See SCI. AM. SUPPLEMENT No. 577.]

The air was obtained one-half meter from the ground and about 100
meters from any of the university buildings. The number of volumes of
carbonic acid is calculated at zero C. and normal pressure 760 mm.

--------+----------+--------------+------------------------
| | Vols. CO_{2} |
Date. | Bar. | in 100,000 | State of Weather.
| Pressure | Vols. Air. |