Page:Popular Science Monthly Volume 52.djvu/443

Rh deciduous. It is probably the Fraxinus chinensis, a species of ash. The tree is known to the Chinese as pai la shu (white-wax tree). On the arrival of the scales from the Chien-ch'ang Valley, they are made up into small packets of from twenty to thirty scales, each inclosed in a leaf of the wood-oil tree. The edges of the leaf are tied together with rice straw, by which also the packet is suspended close under the branches of the wax tree. A few holes are made in the leaf, so that the insects may find their way through them to the branches. On emerging from the scales the insects creep along the branches to the leaves, where they stay for a period of thirteen days. They then descend to the branches and twigs, the females probably to provide for a continuation of the race by developing scales in which to deposit their eggs, and the males to excrete the substance known as white wax. Whether or not this wax is normally intended as a protection for the scales is uncertain. The wax first appears as a white coating on the under sides of the boughs and twigs, and looks very much like sulphate of quinine. It gradually spreads over the whole branch, and attains after three months a thickness of about a quarter of an inch. The branches are then lopped off and as much of the wax as possible removed by hand. This is placed in a pot of boiling water. The wax, melting, rises to the surface, is skimmed off, and placed in a round mold, whence it emerges as the white wax of commerce. An inferior darker quality is made by boiling twigs and all together. When the branches are lopped off a wax tree, a period of three years is allowed to elapse before the tree is again used. Since the introduction of kerosene oil into China the use and hence production of this wax have much decreased, it having been largely used as an external coating for candles on account of its high melting point (160° F.).

Psychic Development of Cats and Dogs.—Prof. Wesley Mills's experiments on the psychic development of young animals continue to be very interesting. In the kitten, while the first stages are very slow and obscure, the author finds that in the progress of all the senses to full development the course, while marked by definite steps, is often so rapid that distinct advances may be marked in a single day. Apart from the senses, etc., there seems to be a definite order in which all the features of feline nature appear, as, for instance, purring, crouching, stalking, etc. Certain physical changes are correlated in time with certain psychic developments, the significance of which is in some cases clear, in others obscure. Comparing the two animals, the cat, on the whole, develops more rapidly than the dog, the greatest difference between them appearing in the social and gregarious nature of the dog and the independent and solitary traits of the cat. The dog is docile in the highest degree; the cat to a slight degree, compared with its intelligence. The play instinct is early and highly developed in both, and the peculiar qualities of each are well exhibited in the manifestation of it. In will power and ability to maintain a separate existence the cat is superior to the dog. In the higher grades of intelligence the wisest dogs are much in advance of the most knowing cats; and this is foreshadowed if not exemplified in the early months of existence. The nature of the dog as compared with the cat tends to beget prejudices in his favor with the mass of persons, so that in general the dog is overestimated and the cat underestimated with the great majority; at the same time the dog's nature is much nearer that of man than the cat's. "The kitten may amuse, but even a puppy dog touches chords of sympathy in the heart of man that the cat can never reach."

An Incandescent Oil Lamp.—Ever since the successful introduction of the incandescent mantle in gas lamps, inventors have been hard at work trying to construct an oil lamp which could be used to replace the gas in heating the mantle. Many such lamps have been contrived, but up to the present time none of them have proved satisfactory. It is now announced, however, in Industries and Iron, that such an oil lamp having an atmospheric burner has recently been offered for inspection in London, which seems to be free from most of the defects of its predecessors, and which promises to become a great commercial success. It is called the "Era" incandescent petroleum burner, and consists of a "gallery burner," spreader, mantle, and chimney—in fact, everything