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THE POPULAR SCIENCE MONTHLY. 



directly from green among our native plants, 

 and doubts if any pure yellow ever immedi- 

 ately 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 Moiiot-opa unijlora, 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 Sjcii- 

 ranthcs 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 gi'cen 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 chloro- 

 phyl 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, " with- 

 out a single exception every flower that 

 came to hand of a white color was developed 

 directly from green, without any intervening 

 color." 



€anaries> — A correspondent of the Lon- 

 don Spectator writes chattily of his pet ca- 

 naries, and seems to show that they are very 

 human in their reason and unreason. Dur- 

 ing some intensely hot weather, when the 

 ben 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 re- 

 fresh 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 pro- 

 cesses that depend on reactions which are 

 set up by submitting chemical systems to 

 electrical stress. Attention is at present 

 concentrated on the production of alumi- 

 num. Sodium, also, is of growing impor- 

 tance, 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 valu- 

 able qualities may be conferred on a mass 

 of metal by a very small quantity of an- 

 other element. The useful qualities im- 

 parted to platinum by iridium are well 

 known. A small quantity of tellurium 

 obliterates the crystalline structure of bis- 

 muth ; but we have lost an ancient art, 

 which enabled brittle antimony to be cast 

 into useful vessels. Two tenths per cent 



