to not more than twenty millimetres. Then if a hydrocarbon is
present, the passage of a spark from a Ruhmkorff's coil will cause the
appearance of a sky-blue light. Viewed with the spectroscope, this
presents the spectrum of carbon, and generally so brilliant as to mask
totally the spectra of other gases present.

The rare metals cerium, lauthanum, and didymium have been lately
investigated by Drs. Hillebrand and Norton, in Bunsen's laboratory.
Cerium looks like iron, having both its color and lustre, but is
heavier, and has the hardness of calcite. It tarnishes slowly in dry air
and rapidly in moist air. It ignites so readily that pieces scratched
off inflame, and its wire burns more brilliantly than magnesium wire.
Lauthanum is a little harder, but also a little lighter. It tarnishes
more easily and inflames less easily than cerium. Didymium resembles
lauthanum. The metals were all obtained by electrolysis of the
chlorides.

It is stated that a week's work in Birmingham comprises, among its
various results, the fabrication of 14,000,000 pens, 6,000 bedsteads,
7,000 guns, 300,000,000 cut nails, 100,000,000 buttons, 1,000 saddles,
5,000,000 copper or bronze coins, 20,000 pairs of spectacles, six tons
of papier mache wares, over L30,000 worth of jewelry, 4,000 miles of
iron and steel wire, ten tons of pins, five tons of hairpins and hooks
and eyes, 130,000 gross of wood screws, 500 tons of nuts and screw bolts
and spikes, fifty tons of wrought iron hinges, 350 miles' length of wax
for vestas, forty tons of refined metal, forty tons of German silver,
1,000 dozens of fenders, 3,500 bellows, 800 tons of brass and copper
wares--these, with a multitude of other articles, being exported to
almost all parts of the civilized world.

The aerated beverages of which Americans are so fond should not be kept
in copper vessels, for carbonic acid (which is the gas present)
dissolves this metal with great avidity. From three-hundredths to
one-tenth of a grain of copper per gallon has been found in aerated
lemonade, ginger ale, soda water, etc.

In making the ultimate analysis of organic compounds by combustion, with
lead chromate and metallic copper reduced by hydrogen, the results
obtained are too high, on account of the expulsion of hydrogen, which
had been occluded by the copper. Heating the copper to 150 deg. C. does
not prevent the error, which may be .05 per cent.

Mayer & Walkoff, who have been experimenting on the