Draper at Central Park, was 52.25 inches, somewhat
higher than usual, as the average for a series of years before gives 46
inches; but taking these former figures, we find that for that year
(1884) each acre of ground received, accepting the results obtained by
my examination, 76.24 avoirdupois pounds of common salt, if we regard
the entire chlorine contents of the rains as due to that body, or 46.23
pounds of chlorine alone.
In comparison with this result, we find that at Caen, in France, an
examination of the saline ingredients of the rain gave for one year
about 85 pounds of mineral matter per acre, of which 40 pounds were
regarded as common salt.
Although chlorine is almost constantly present in plant tissues, it is
not indispensable for most plants, and for those assimilating it in
small amounts, our rainfall would seem to offer an ample supply. These
facts open our eyes to the possible fertilizing influence of rains, and
they also suggest to what extent rains may exert a corrosive action when
they descend charged with acid vapors.--_L.P. Gratacap, in School of
Mines Quarterly_.
* * * * *
THE CHROMATOSCOPE.
Some time ago Mr. J.D. Hardy devised an instrument, which he has named a
chromatoscope, so easily made by any one who has a spot lens that we
take the following description from the _Journal_ of the Royal
Microscopical Society: "Its chief purpose is that of illuminating and
defining objects which are nonpolarizable, in a similar manner to that
in which the polariscope defines polarizable objects.
Pages:
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159