To complete the subject, we shall proceed to describe the construction of these valves, of the uses of which we have only yet spoken : they are of three kinds, and were the subject of a patent granted to Mr. Gordon.
The annexed engraving gives a sectional view of an improved stop-valve (similar to those attached to the principal recipient i), especially adapted for transfer ring the compressed gas from one vessel to another, without occasioning loss during the process. It is composed of two pieces of metal, A and B, which are screwed together with a soft metal collar between them at a a ; e e represents the openings through which the gas is allowed to pass. The piece A has the regulating steel screw c tapped through it, being formed at the lower part with a double cone, one part of which cone is adapted to fit correctly into the cavity in the under side of the piece A. Now when the lower cone of the regulating steel screw is screwed or forced tight down into the conical seat in the piece B, it prevents all escape of the gas ; and when it is desired to transfer compressed gas from one lamp or reservoir to another, the regulating screw c is to be turned until its upper cone fits and applies correctly into the conical cavity of the piece A, and thereby prevents all escape of the gas up the threads of the regulating screw during the process of transferring, allowing, at the same time, free pas sage of the gas from one reservoir to another, through the openings e e.
The next valve to be described is the one which is fixed at the bottom of each reservoir or lamp, for the purpose of filling them in the manner described in the preceding part of our subject; the annexed cut represents a sec tion of one of those valves. This filling valve consists of a small conical plug ,q, which is fitted into a conical cavity or seat in the piece of metal c, similar to the valves of an air-gun, being closed by a slight steel spring h, and guided in its way by a metal pin, which slides through a hole in a small brass cap or per forated cover i, represented as screwed over it ; d shows a brass plug, which is intended to be screwed into the lower aperture of the piece c, after the filling is completed. The upper surface of this screw-plug is furnished with a soft metal ring or collar, b b (as in the before-mentioned valve), which being pressed, by the force of the screw, into contact with the under side of the piece c, effec tually prevents any escape of the gas from that end of the reservoir, even if the filhng valve g should not be quite air-tight.
The following figure represents a section of the third and last of these valves, and its use is to permit the flow of gas to the burner to be regulated with great nicety and precision. The passages for the gas, e e, are drilled out of one solidpiece of metal, and the regulating screw c is tapped into the side of the same piece ; the lower part of it is adapted to screw into an aperture at one end of the reservoir of the lamp, when the regulating steel screw c is screwed up so that its conical end fits tightly into the conical cavity,—it closes it perfectly, and prevents all escape of gas to the burner a; but on turning the regulating screw slightly round by its square head, the gas escapes through the pas sages e e to the burner, in any degree that may be desired. Previously to in
serting the regulating screw, it is dipped into a mixture of bees' wax and oil, which fills up every minute cavity or space which may be left between the threads of the two screws.
The engraving on page 602 represents a contrivance for delivering gas to the consumers in its natural volume, under atmospheric pressure. It consists of a collapsing gasholder, capable of containing upwards of 1000 cubic feet of gas; it is mounted on wheels ; and being charged at the gas works, the gas is con veyed wherever required. The invention forms the subject of a patent to Messrs. Coles and Nicholson, and is, we believe, made use of by the Portable Gas Company at Manchester, in addition to the gas-condensing apparatus erected at their works at that place. Fsg. 1 represents a plan of the cart, with the top of it removed ; Fig. 2 is a side elevation, and fig. 3 a front elevation ; $g. 4 is merely an enlarged section of the box marked d in Fig. 2. The recipient is composed of two distinct parts or halves, a and b ; the upper part a is made of some flexible material, impervious to gas; and the lower part b of some com paratively stiff and inflexible substance ; when the vessel is empty, the part a, turning itself inside out, falls down inside of b; the vessel is filled by forcing the gas from the works through a pipe, which is screwed into a nozle at f, pro vided with a stop-cock, which is turned off after the recipient is fully inflated, and the supply pipe from the works removed. The machine then travels through the streets, and stopping at a customer's door, one end of a flexible pipe is screwed into the gasholder of the house, and the other end into a nozle in the box d, which communicates with the interior of the recipient by means of intermediate valves shown at Fig. 4. The gas-exhauster c is then put in motion by the handle at the top, and at every exhausting stroke is filled with gas from the gas cart through the valve g, Fag. 4 ; ,and at each forcing stroke, the gas is discharged through the valve h, and along the flexible pipe into the gasholder of the house, until the required quantity III transferred. The gas cart thus proceeds from house to house, until the whole load is discharged. Along the bottom of the cart is a pipe e, connected at one end with the stop-cock f, and at the other with the box cl of the exhauster, and perforated with nume rous small holes, for the purpose of allowing the passage of the gas along the bottom of the cart when the flexible top lies over it. Since the foregoing account of the Portable Gas Machinery was prepared for the press, we have been informed that it has been nearly superseded by subsequent improvements in the manufacture and management of coal gas; nevertheless, the subject pos sesses sufficient intrinsic merit for our pages, as much of the mechanism is applicable to other purposes.