Art. XVIII. A Substitute for Woulfe's or Nooth's Apparatus.
Art. XVIII. A Substitute for Woulfe's or Nooth's Apparatus, by Robert Hare, M. D. Professor of Chemistry in the Medical Department of the University of Pennsylvania, and Member of various Learned and Scientific Societies. With a Plate.
Few subjects have more occupied the attention of chemists, than the means of impregnating fluids with gaseous substances. The contrivances of Woulfe and Nooth, especially the former, have been almost universally used; and have gained for the inventors merited celebrity. Various improvements in Woulfe's bottles have been devised. Still I believe an apparatus replete with similar advantages, but less unwieldy, less liable to fracture; and having fewer junctures to make at each operation, has been a great desideratum with every practical chemist. It has, however, ceased to be so with me, since I contrived the apparatus which I am about to describe.
Fig. 1. represents 3 jars placed concentrically within each other, and so proportioned and situated, as to admit 2 open-necked concentric bell glasses alternately between them. The neck of the exterior bell glass is introduced into the tubulure of the receiver above, and receives the neck of the interior bell glass. Into this is inserted a trumpet-shaped tube. The two interior jars are furnished with feet F, f. In order to put this apparatus into operation, remove (without taking them apart) the bell glasses, receiver, and tube from the jars. Pour into the latter the fluid, to be impregnated, till it reaches the height marked by the dots. The funnel mouth, m, of the receiver being provided with a suitable cork soaked in wax, fasten into it firmly the beak of the retort, containing the generating materials. The bell glasses are then to be replaced in the jars, and arranged as in the figure. It must be self-evident that the gas proceeding from the retort, (if the juncture at m be air tight) must press on the fluid in the innermost jar, through the trumpet-shaped tube. If not imbibed with adequate speed, it must soon press on the fluid at a, causing it to subside to the narrow part of the foot f, and thus to expose a much larger surface. If the absorption be still inadequate, a further subsidence must ensue, and the gas escaping round the brim of the interior bell glass will act on the fluid at b, and enlarge its surface by depressing it to the narrow part of the foot F. Should the increased pressure and more extended contact thus obtained, be still incompetent to effect a complete absorption, the excess of the gas may escape round the brim of the external bell glass into the atmosphere.
Drawn & Engraved by Kneass, Young & Co.
But so effectual is this process in promoting impregnation, that I have obtained strong muriatic acid in the central jar, without producing any sensible acidity in the outside one. Absorption into the retort or receiver, is prevented by not allowing as much fluid to be above the mouth of the trumpet-shaped tube, as would be competent to fill the cavity between it, and the termination of the open neck of the exterior bell glass at t. As this neck rises about 2 or 3 inches into the receiver, it prevents any foul matter which may condense or boil over, from getting into the jars. If practicable, it would be better that the bell glasses, and tube, and receiver, should be united together while hot, at the glass-house. If all could not be joined in this way, it would still be advantageous to unite thus the receiver, and the exterior bell glass. The interior bell and tube might then be fastened together, by grinding or luting. As yet I have only used lutings of waxed cloth, or cork. It may be proper to point out, that 3 or more concentric bell glasses, and 4 or more jars, might be used. The union of the bells, receiver, and tube once effected, it is hardly more troublesome to use 3 than 2. When the fluid in the central jar is saturated, this may be emptied and replenished from the middle jar, the latter from the external one. Then supplying the external jar anew, the process may be continued.
The other figures are to explain an apparatus on the same principle, constructed of hollow, oblong paralellopipeds, differing in length more than in breadth; so as to allow a serpentine tube to wind into the interior, and deliver gas under a vessel shaped like a T.
Fig. 2. represents a vertical section of the whole as when situated for use.[74]