M. Henri Sainte-Claire Deville has recently presented to the French Academy of Science the third portion of his valuable researches on the physical and heating properties of mineral oils. M. Deville, in this memoir, dwells largely on the dangers incident to the use and storage of petroleum, and on ike modes of preventing the disasters which are of such frequent occurrence. Most persons suppose all such cases to be due to one cause nly; namely, to the highly inflammable nature of the volatile ingredients contained in these oils, which, by admixture with air, form explosive compounds. This is a cause of real danger, but the above-named chemist calls attention to a hitherto unnoticed reason for many fires and accidents. This he attributes to the very great expansion in bulk which mineral oils undergo by increase of temperature. If pelroleum has been barreled during the cold season, it will expand larg@ly vrith. the first appearance of hot weather, and will then burst the containing vessels, on the same principle that ice ruptures our water conduits and hydrants. The inflammable material then oozes out, often without being noticed, and is a lurking cause of danger. It is well known that the burning of petroleum refineries and storehouses gen- erally takes place in hot weather after a cool period has just elapsed. Now is the time of the year to look out for petroleum fires, and to see to their prevention. The conclusion to be derived from M. Deville's memoir is, that it is essential to leave sufficient space for expansion by heat in all vessels containing petroleum, and never to fill them to repletion. When the paper of M. Deville shall have been published, we shall be able to tell our readers the exact extent of space needed for the mean expansion of all mineral oils. This statement, taken in connection with the very recent and destructive oil-fires at Hunter's Point, L. I., and at Wee-hawken, N. J., occurring under the precise conditions of temperature described by Mr. Deville, will attract much attention.