RESPIRATOR, or breath-warmer, an instrument, invented and brought into use by Mr. Julius Jeffreys, for giving warmth to the air drawn into the lungs in breathing, and thereby enabling invalids to enjoy the benefits of exercise in the open air without Injury or inconvenience.
The common practice of wrapping up the lower part of the face in a woollen covering warms the air inhaled through it very imperfectly, and in an unwholesome manner, by mixing with it a portion of the impure air exhaled from tho lungs, and detained in its bulky folds. A woollen wrapper, being a non-conductor of heat, can act in no other way. In the respirator this disadvantage is avoided by causing the air discharged from the lungs to pass through several layers of very fine wire, fixed so near together that the breath passing through them is almost infinitely divided, its warmth being abstracted by the metal, which, being an excellent conductor of heat, freely imparts it to the fresh cold air drawn, or, as it were, filtered through it. The compact of the instrument is such that there is no room for the lodgment of the impure air expelled from the lungs, and consequent contamina tion of that inhaled; and the condensation of moisture on the wires corrects the injurious dryness of the atmosphere in some northerly winds.
The means by which these objects are attained in the respirator display much ingenuity in contrivance, and no ordinary degree of skill in the execution. The inventor considers it necessary that about twenty layers of metal-work should be used, and, in order to make the instrument as light and compact as possible, each layer is required to be exceedingly thin. The apparatus usually consists of from eight to twelve frames of sheet-silver or other metal, about three inches and a half long, one inch and a half wide, and part of an inch thick ; the metal of which is pierced away by machinery so as to leave merely a narrow frame containing six vertical bars of and five horizontal bars Atli of an inch wide. On both sides of each of these frames a layer of wires an iuch and a half long and of an inch thick is soldered, care being taken to connect each wire, not only with the top and bottom bars of the frame, but also with each of the five horizontal bare. The wires are Laid about y th part of an inch apart, and are so numerous that a large respirator of high power contains 2000 feet of wire, divided into about 12,000 pieces, and soldered to the frames at more than 80,000 distinct points. - The frames or lattices of wire-work
are fixed parallel to each other, and kept a short distance apart by small studs of a substance which is a slow conductor of heat, so that the inner layer is always kept, as nearly as possible, at the temperature of the air expelled from the lungs, and each successive Layer diminishes in warmth, till the outer one is nearly as cold as the external air. The curious and philosophical application of a non conducting medium between the metallic screens is essential to the perfect action of the instrument, as without it the heat would be equally diffused, and no part of the metal-work could retain more than half the temperature of the breath. By this arrangement the air inhaled, finding each layer of wire warmer than the preceding, is gradually raised, in respirators of the highest power, to the greatest attainable temperature. The most powerful respirators have twenty-four layers of wire-work, those of medium power sixteen, and the lowest power eight. The whole of the wire-work is bent into a curved form, and enclosed in a bordering or case of soft leather, which is made to fit closely to the face of the wearer, so as to prevent the entrance of air otherwise than through the metal-work, and to hold the latter in such a position that the lips du not come in contact with the wires. An outer covering of silk or other material is added, having an aperture in which is inserted a very thin plate of silver, perforated with minute holes, and to which a dark colour is imparted by a chemical operation, to servo as a screen to the wire-work, which it hides without impeding the passage of air as most textile fabrics would do. Recently however a very fine and open woollen fabric has been made use of in lieu of the perforated plate, to suit the wishes of some persons to whom the appearance of the instru ment was an objection. The common or oral respirator covers the mouth only ; but a variety called the mimosa/ respirator encloses the nostrils also. A piece of sponge attached to the lower edge of the instillment collects the moisture condensed from the breath, and it, as w ell as the metal-work and leather mounting, may be detached from the outer covering and cleaned when necessary.