Page:Popular Science Monthly Volume 16.djvu/601

 change, since the effect is immediate in charging and discharging. Neither can electric pressure cause it, because that must be the same on both sides of the dielectric, and a diminution of volume would be the result. Again, it is not due to the polarity of the armature, for on reversing the poles the effect is the same.

Sheep poisoned at Pasture.—If we regard the masses of its bloom, and the exceptionally exquisite form of its blossoms, probably no flower can equal the kalmia, or American laurel. All this is appreciated in Europe, and the plant holds a distinguished place in its gardens. But at home this fine shrub bears the execration of all shepherds and herdsmen, as it is poisonous to the sheep. Next to Australia, if not equal, in sheep-raising, is Colorado. Unhappily, a poisonous mallow (Malvasirum coccineum) is found growing from Iowa across the great Plains westward. Last October a sheep-raiser named Ruble, in Pueblo, Colorado, had the ill luck to have a flock get into a patch of this terrible weed, and twelve hundred sheep perished in four hours! Another plant in Colorado, the dreaded "loco" of the stock-men—the Oxytropia Lamberti—is also noted for its poisonous qualities.

A Precocious Century-Plant.—There is now (January) a fine century-plant (Agave Americana) in full bloom, in the conservatory of John Hoey, Esq., at Hollywood, Long Branch, New Jersey. This plant is only twelve years old. The notion of this aloe only blooming when a hundred years old is simply a tradition of the elders. It all depends on the environment and chiefly temperature. Blooming at the age of fifty years is common. To get the plant into bloom at twenty-five years is considered quite satisfactory by the gardeners, but this instance of one flowering at twelve years, in a conservatory, must be accounted as unique.

The Proportion of Oxygen in the Upper Air.—Though oxygen is heavier than nitrogen, and therefore ought to fall to a lower level in the atmosphere than the latter gas, still, no difference has ever been found to exist in the relative proportions of the two, even at the greatest attainable altitudes. Up to such elevations the agitation of the air suffices to keep its components uniformly mixed. Whether there is any want of uniformity at still greater elevations is an open question, the solution of which has been attempted by Professor Edward W Morley, of Hudson, Ohio. Accepting as provisionally correct the theory proposed a few years ago by Professor Loomis, that great and sudden depressions of temperature are sometimes owing to the vertical descent of cold air from elevated regions of the atmosphere, Professor Morley inferred that samples of air taken at the earth's surface during a great and sudden lowering of temperature might have come from altitudes where the proportion of oxygen had been lessened by the action of gravity. He has therefore made numerous analyses of air during "cold waves," and the result has been invariably to show deficiencies in the proportion of oxygen in the air at such times.

New Coloring Matters.—The chemists Savigny and Colineau have discovered a method of obtaining innocuous coloring matters from the red cabbage. This substance is known as cauline, and is useful in painting, for printing fabrics, and for dyeing. The process is as follows: Cut the interior of the cabbage and the stalks of the leaves in small pieces and place them in boiling water in the proportion of one and a half kilogramme of leaves to three litres of water. The infusion is left about twenty-four hours to macerate, then the leaves are taken out and submitted to pressure to squeeze out the water, which is added to the liquid infusion; this cauline is of a violet-blue color. It forms the base of a series of derivatives which constitute the precipitates of various colors. For instance, to obtain barucauline, two grammes of baryta are added to five hundred grammes of cauline cold; this produces a clear green dye. To obtain chlorocalcicauline, which is a bluish green, one hundred grammes of anhydrous chloride of calcium are added to half a kilogramme of cauline. A false bronze color is obtained by adding one hundred to five hundred grammes chloride manganese and five grammes baryta to five hundred grammes cauline; this is called