Mr. A. Allard, starting from the fact that the richness in starch increases along with the density, has constructed a simple apparatus that gives both these data at once, with sufficient precision, and without calculations, tables, etc. It is, upon the whole, a large areometer with constant weight and variable volume that is plunged into a cylindrical vessel 0.5 m. in depth and 0.3 m. in diameter, filled with water. The instrument itself consists of three parts: (1) A lower receptacle in which is placed a weight to assure the equilibrium; (2) a central float into which is put a kilogramme of very clean and very dry potatoes; and (3) a rod graduated for density and feculometric richness. The deeper the apparatus sinks, the more valuable is the potato. How much more? The degree to which the rod sinks shows this. The same principle and the same instrument might be applied to the determination of the density of various agricultural products, such as beets, cider fruits, grain, etc. It would suffice to graduate a special scale each time. For each variation of a thousandth in density, the areometer sinks about 5 millimeters--that is to say, it presents a sensitiveness that is more than sufficient in practice.--Le Monde Illustré. * * * * * THE COMING LIGHT. There is no more eager contest than that which has been going on for some time between gas and electricity. Which of these two systems of lighting will triumph? Will electricity suppress gas, as gas has dethroned the oil lamp? A few years ago, the answer to this question would not have been doubtful, and it seemed as if gas in such contest must play the role of the earthen pot against the iron one. At present the case is otherwise. The Auer burner has re-established the equilibrium, and the Denayrouse burner is perhaps going to decide the fate of electricity. As naturalists say, the function creates the organ, and it is truly interesting to observe that in measure as the need of an intenser and cheaper light grows with us, science makes it possible for us to satisfy it by giving us new systems of lighting or by improving those that we already have at our disposal. What a cycle traversed in twenty years! What progress made! Let us remember that the electric light scarcely became industrial until the time of the Exposition (1878), and that the Auer burner obtained the freedom of the city only five or six years ago. Is there any need of recalling the advantages of these two lights? In the first, a feeble disengagement of caloric, automatic lighting and a steadier light; in the second, a better utilization of the gas, which gives more light and less heat.