Page:Popular Science Monthly Volume 40.djvu/738

718 directly from green among our native plants, and doubts if any pure yellow ever immediately succeeds green. But there are some greenish-yellow flowers. For illustration of the normal floral method of development by which he believes all the bright, attractive hues of the floral world are produced, the author takes up the Spiranthes gracilis, or ladies-tresses, an orchid which grows in all our fields, having small white flowers spirally disposed at the summit of the scape. The lip is green, fringed around the edges with white, and the other petals are wholly white. "A small section of the petals, placed under the magnifying glass, appears colorless and transparent, while the delicate network of the tissue glistens like crystal; yet this colorless tissue, in a mass, reflects white. In the same manner a single leaf-like bract of Monotropa uniflora, severed from the stem, appears colorless; but two or more placed together, making a greater thickness, reflect a decided white color." Attention is called to the fact that in Spiranthes the white color directly succeeds the dark rich green of the lip. The author then endeavors to demonstrate that the universal law of progression in color, as regards the floral structure, is first from green to white; "or, differently stated, Nature, before she begins to paint the more rich and delicate tissue of the petals, by some secret chemical process completely eliminates the chlorophyl and prepares a perfectly pure and white canvas upon which to essay higher flights of fancy." Twenty-eight wild and garden flowers are cited as illustrating this principle in the development of their colors, and numerous inconspicuous or weed-like plants in the coloring of their sepals; while the hues of flowers of other colors are thus produced by transition through white, "without a single exception every flower that came to hand of a white color was developed directly from green, without any intervening color."

Canaries.—A correspondent of the London Spectator writes chattily of his pet canaries, and seems to show that they are very human in their reason and unreason. During some intensely hot weather, when the hen was sitting, she drooped, and it seemed as if she might not be able to hatch her eggs. The cock, however, showed himself an excellent nurse. After bathing in fresh cold water, he went every morning to the edge of the nest and allowed the hen to refresh herself by burying her head in his breast. A green and yellow canary hung side by side, and were treated exactly alike. One day three dandelion blossoms were given to the green bird and two to the yellow one. The latter showed his anger at the proceeding by "flying about his cage, singing in a shrill voice." But when one of the three flowers was taken away, both birds seemed quietly to enjoy their feast.

Utilizing the Less-known Metals.—In closing his presidential address before the Chemical Section of the British Association, Prof. Roberts-Austen spoke of the great importance of extending the use of the less-known metals. He supposed that in the immediate future there would be a rapid increase in the number of metallurgical processes that depend on reactions which are set up by submitting chemical systems to electrical stress. Attention is at present concentrated on the production of aluminum. Sodium, also, is of growing importance, both for cheapening the production of aluminum, and as a powerful weapon of research. The manufacture of magnesium, which was a curiosity in 1849, has become an important industry. We may confidently expect to see barium and calcium produced on a large scale as soon as their utility has been demonstrated by research. Minerals containing molybdenum are not rare; and the metal could probably be produced as cheaply as tin if a use were to be found for it. The quantities of vanadium and thallium which are available are also considerable; but we as yet know little of the action when alloyed of those metals which are in daily use. The field for investigation is vast, for it must be remembered that valuable qualities may be conferred on a mass of metal by a very small quantity of another element. The useful qualities imparted to platinum by iridium are well known. A small quantity of tellurium obliterates the crystalline structure of bismuth; but we have lost an ancient art, which enabled brittle antimony to be cast into useful vessels. Two tenths per cent