Chap. 6.]

Wirtemburg and Argand’s Siphon.

525

long siphons ; the former being applied to the discharging, and the latterto the receiving orifice.

Of devices for stopping and rene wing the discharge without either cocksor valves, the Wirtemburg siphon is the oldest. It was so named fromits invention in that city. The legs are of equal length, and to preventthe admission of air when the instrument is not in use, their ends are bentupwards. See No. 256. (For the convenience of discharge, one end iscommonly recurved.) The alledged advantages of this siphon over otherswere more imaginary than real. It was at one time announced as “ a veryextraordinary machine, performing divers things which the common siphoncannot reach.” Thus, when the legs were inserted in different vessels, itwas said to preserve. the liquid at the same level in both ; and althoughthe legs were of equal length, water rose indifferently up one and descend-ed through the other, besides other properties which in fact are commonto all siphons. Its only peculiarity consists in the ends of the legs beingturned upwards, so as to retain the fluid within, and thus be always readyfor use : but this retention of the contents, although theoretically true, isin p^actice hardly attainable, since it requires the orifices to be alwayspreserved on the same horizontal line—a condition extremely difficult toperform, except with very small instruments, and whose ends are turnedconsiderably up. If the ends reach only to a level with the upper side ofthe flexure, the slightest change of position makes one leg longer than theother; air is admitted, and in a moment the whole contents are expelled.A siphon thus made of inch, or ^ inch tubing, could not be moved fromone vessel to another, or hung against a wall, without the contents beingdisplaced. Disks or Stoppers placed over the orifices would prevent this,but they would virtually be valves. The Wirtemburg siphon is conse-quently seldom seen except in the lecture room. (See Phil. Trans, xv,846-7, and Lowthorp’s Abridg. i, 537-9.)

In 1808, M. Argand, the inventor of lamp burners that go under his

name, devised a “ valve siphon” preciselysimilar to No. 253. From remarks madein the journals of the time, he seems to havebeen considered the introducer of the valve—an erroneous idea. As regards the con-JL. struction of his siphon all that could be claim-E : by or for him was the mode of connectinggl|jf the legs to the horizontal part by screws, sothat they might easily be separated, eitherfor the purpose of cleaning or more con-veniently packing. But Argand’s mode ofcharging his siphon was novel. It waseffected on the same principle as water israised by the canne hydraulique, (page 372,) viz. by moving the instru-ment perpendicularly up and down in the liquid, until it became. filled.Instead of imparting motion to the whole instrument, which in larger oneswould be inconvenient, M. Hachette suggests that the lower part of thereceiving leg be connected to the upper part by a flexible tube of leatheror cloth impermeable to liquids, so that the part in which the valve issituated need only be moved. See No. 257.

Siphons are necessary in numerous manipulations of the laboratory, andmodern researches in chemistry have given rise to several beautiful devicesfor charging them, and also for interrupting and renewing their action.When corrosive liquids or those of high temperatures are to be transferredby siphons, it is offen inconvenient, and sometimes dangerous to put them

No. 256.