To discover by the spectroscope the smallest quantity of a gaseous or very volatile hydrocarbon, the Messrs. Negri introduce a small quantity of the gaseous mixture into a tube. This mixture should not contain oxygen, carbonic oxide, or carbonic acid; and the pressure is to be reduced 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 maché wares, over £30,000 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 aërated 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 aërated 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 respiration of plants, find that the action goes on both in light and darkness, and that changes of temperature within normal limits have little effect. There is no direct relation between growth in length and respiration, a conclusion that is in conflict with that of previous experiments.
The famous "Blue Grotto" in the island of Capri, Italy, has been investigated spectroscopically. Most of the light enters through the water, which absorbs the red rays entirely and so much of the yellow as to make the D line scarcely visible. The green, blue, and indigo rays are very bright, and the F and b lines unite in a well marked absorption line.
The springs of Weissenburg in the Bernese Oberland yield a water which is popularly supposed to have the power of cicatrizing cavities in the lungs, but its analysis shows no reason for such a power. Sulphates of lime and magnesia are its principal solid ingredients, with chloride and a little iodide of lithium and an organic compound having the odor of blackberries.
The mountains about Innsbruck in the Tyrol, as well as other parts of the Alps, present the singular phenomenon of a climate more moderate at a considerable elevation than in the valleys. Prof. Kerner finds that there is a warm region midway up the mountain, lying between two colder zones above and below it. We have heretofore referred to a similar phenomenon in Indiana.
It is remarked by anthropologists that differences of color are one of the most marked signs of race. The Aryan word for caste is Varanum, meaning color, and the Aryans are supposed to have used it to distinguish themselves from the Dasyuf, with whom they came in contact on crossing the Indus, when migrating from Central Asia. The first migrating wave from that centre of human creation can no longer be traced, and only its remnants are found among the most degraded of the hill tribe and slave population in India. Prof. Rollesten thinks that the earliest races of man were preëminently of the Australioid type, which is now brown-skinned and wavy haired, with long narrow heads.