It is found that insects preserve their colors better under yellow glass than in any other color. The curtains of entomological show-cases and the blinds of the room should be yellow. Only in this way can the delicate carmine tints of some insect wings be preserved.
A student of animal nature announces a case of two hens, who by joint efforts hatched one chick. They have since, for some weeks, been parading the yard, each clucking and manifesting all the anxiety and care of a true mother over this one. The hens never quarrel, or show the least appearance of jealousy or rivalry.
M. Tresca, who has charge of the Conservatoire des Arts et Métiers, the institution which in Paris answers to our Patent Office, says that drawings of new inventions are more useful than models, are cheaper, and are very much oftener consulted. In Paris the model room is covered with dust and rarely entered.
The French weather bureau intends not only to study the thunderstorm, hailstorm, rainfall, inundations, and frosts, with especial reference to their effects upon agriculture, but also to experiment upon the asserted effect of smoke as a preventive to frost. The experiments will be extensive and may cover a large valley.
To discover by the spectroscope the smallest quantity of a gaseous or very volatile hydrocarbon, the Messrs. Negri introduce a small quantity of the gaseous mixture into a tube. This mixture should not contain oxygen, carbonic oxide, or carbonic acid; and the pressure is to be reduced to not more than twenty millimetres. Then if a hydrocarbon is present, the passage of a spark from a Ruhmkorff's coil will cause the appearance of a sky-blue light. Viewed with the spectroscope, this presents the spectrum of carbon, and generally so brilliant as to mask totally the spectra of other gases present.
The rare metals cerium, lauthanum, and didymium have been lately investigated by Drs. Hillebrand and Norton, in Bunsen's laboratory. Cerium looks like iron, having both its color and lustre, but is heavier, and has the hardness of calcite. It tarnishes slowly in dry air and rapidly in moist air. It ignites so readily that pieces scratched off inflame, and its wire burns more brilliantly than magnesium wire. Lauthanum is a little harder, but also a little lighter. It tarnishes more easily and inflames less easily than cerium. Didymium resembles lauthanum. The metals were all obtained by electrolysis of the chlorides.