After closing the cock, j, water is poured into the reservoir, and, running down to the lower compartment, drives out the air through the cock, m. This operation once effected, it only remains to turn off the cock, m, again, and open j in order to establish the normal operation. As the chamber, A, is provided externally with a water gauge, N, it may be seen at a glance when it is necessary to maneuver the cocks in order to expel the air. This system of siphon is evidently applicable to all sorts of liquids. It may likewise undergo a few modifications in its construction; for example, the valve, which in our engraving is placed over the siphon, may be located at any distance from the apparatus, although it should, in all cases, be in constant communication with it by means of a tube, and be placed a little higher than the siphon. It may then be put under cover and be kept constantly in sight, thus greatly facilitating its surveillance. As may be seen, the essential peculiarity of this improvement consists in the very ingenious arrangement that permits of immersing the cocks in the liquid to make them perfectly tight, it being necessary that they should be hermetically closed in order to prevent the entrance of air to the siphon. Everything leads to the belief, then, that if upright siphons have never been able to operate regularly, it has been because no means have been known of expelling the air from the interior without letting air from the exterior enter at the same time. The arrangement devised by Mr. Falconetti gets over the difficulty in a very elegant manner. It seems as if it would be called upon to render great services in the industries, and it well merits the attention of engineers of roads and bridges, and of contractors on public works.--_Revue Industrielle_. * * * * * THE WEIBEL-PICCARD SYSTEM OF EVAPORATING LIQUIDS. In the industries, there are often considerable quantities of liquid to be evaporated in order to concentrate it. Such evaporation is very often performed by burning fuel in sufficient quantity to furnish the liquid the heat necessary to convert it into steam. This process is attended with a consumption of fuel such as to form a very important factor in the cost of the product to be obtained. In order to vaporize, at the pressure of the atmosphere, 1 kilogramme of water at 0°, 637 heat units are required, and of these, 100 are employed in raising the water from 0° to 100° and 537 in converting the water at 100° into steam at 100°. This second quantity is called the _latent heat_ of the steam at 100°. The sum of the two quantities is called the _total heat_ of the steam at 100°. The total heat of the steam remains nearly constant, whatever be the temperature at which the vaporization occurred. [Illustration: THE WEIBEL-PICCARD EVAPORATION APPARATUS.]