Page:Popular Science Monthly Volume 30.djvu/887

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863
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paring fruit for the market and preserving it for family use. The method by evaporation was especially commended. Mr. Ezra Arnold, of Illinois, presented drawings and specifications of a cheap evaporator made and used by himself, with which he had had better success than with the more expensive dry-houses and evaporators. It is very simple in construction, and with it the inventor could dry apples in two hours; straw-berries in three hours; peaches, cherries, and com in two hours, etc. He did not intend to make or sell evaporators, but would consign to the Association his right and title in the invention, provided that body would procure cuts to illustrate the different parts, and would distribute gratuitously complete illustrated directions for making and using the evaporator. His proposition was accepted by the Association. (W, Orlando Smith, secretary, Alliance, Ohio.)

 

The Mexican Luminous Beetle.—Carl Heinemann, of Vera Cruz, has published observations of the Mexican cucuyo [Pyrophorus), or luminous beetle. Each beetle has three lamps—a pair of small lamps on the prothorax, near the margin, and a large lamp in its abdomen, all developments of the hypodermis, and largest in the male. Though the light is usually nocturnal, yet, if the animal is disturbed by day, it will shine, but less brilliantly, and a sleeping cucuyo will show in a dark chamber a mild light; and if at such time it is awakened, and breathing begins, the light will appear in its splendor. There are two degrees of luminosity—one soft and the other bright—which may be termed, respectively, the cell-light and the tracheal light, and one may change into the other by stimulation. In a dark room the light appears clear green, inclining to blue; in daylight it is yellowish. The spectrum analysis has not been satisfactorily effected, but the light seems to produce a spectrum wanting in half the blue and deficient in the red. An extracted luminous organ will continue to give red light for some hours. No light-nerves were found, and so far there was no evidence of the luminosity being under control of the will. The abdominal light, at least, depends only on the respiratory center. The expiration only of the abdomen is active, and the inspiration is the passive act of the abdominal muscles returning to their place of rest. On every such inspiration the air brought by the tracheæ causes the luminous organ to give its bright, steady light. It is manifest that the light depends on a process of chemical oxidation. Mechanical irritation chemicals, and electrical stimulus never succeeded in exciting more than the mild cell-light. But a stream of atmospheric air, or of oxygen, brought out the brilliant tracheal light. For the continuance of the light, both oxygen and moisture are favorable. The luminous process goes along with the production of a greenish-yellow substance which is found diffused in the luminous cells; and this yellow can be fixed. The author believes that a substance is produced in the luminous organ which, on contact with oxygen, burns and gives out light. The ashes produced are rich in phosphoric acid, and from this he concludes that there is a burning of some phosphorous body.

 

Isochromatic Photography.—Mr. Frederic E. Ives, by washing his plates with a chlorophyl solution in addition to the ordinary preparation, takes photographic pictures in which all the colors and tones of color—including those which the ordinary plates do not return—are represented in their proper gradations of light and shade. A chlorophyl solution made from blue-myrtle leaves has been found to be the best, although that from a few other leaves may be equal to it. The quality of the plates, when they are to be used immediately, is improved if the solution contains a trace of eosine. But the chlorophyl solution without the eosine may, by adding a little zinc in the preparation, be kept for a considerable time without losing its efficacy.

 


NOTES.

The "Lancet" sees in precocity simply the early or premature use of the higher cerebral centers, particularly those which stand in near relation to the senses. Even when the higher intellectual centers are affected, the excitation may usually be traced through channels which originate in the senses. The calculating boy is gifted with a specially acute perception of sight- or sound-phantoms, which are so clearly