The object of this arrangement of cocks and reservoir is to prevent the siphon from losing its priming through the possible presence in the transverse portion of a certain quantity of air or gas that might be given off by the water and accumulate in this place.
The compartment, A, of the reservoir, h, is designed for receiving the gases that collect in the top of the siphon, while the upper compartment contains water for making a hydraulic joint, and consequently preventing any re-entrance of air through the apertures in the partition, i.
To prime the siphon, we shut the cocks, e and f, open the valves, j and m, and pour in water until the whole affair (siphon and reservoir) is full; then we close the cock, m, and open the three others. The siphon thus becomes primed, and begins to operate as soon as any water reaches one or the other of the lower receptacles. As the cock, j, is constantly turned on during the operation of the siphon, the air that has been able to accumulate in the lower compartment, A, of the reservoir, h, would finally unprime the siphon by intercepting communication between its two legs. In order to prevent such a thing from occurring, it suffices to expel the air, from time to time, that accumulates in the chamber, A, this being done, without stopping the operation of the siphon, as follows:
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.