The blow-off pipe answers as an outlet for any gases that may form ; it will also prevent overflowing by discharg ing any rising or overheated oil back into reservoir. The steam-pipe serves to blow out and clean the whole apparatus from time to time, as well as to warm the oil.
The Baker Oil Filter is shown in Fig. 2. The oil enters at the bottom, passes into a body of water, and floats upward through the chamber of filtering material, as shown in the cut, and settles above the water. Centrifugal machines especially construcwd for the pur pose are commonly used for extracting oil from filings, shavings, new process of engraving, which consists in tracing, by means of an incandescent point, upon wood, leather, bone, ivory, fabrics, etc., designs which, varied in tom., depth, and tinting, through a carbonization more or less complete, and more or less pronounced, produce extremely varied and re markable effects in the hands of the artist. The pvro-gravure apparatus, devised by Mr. Perier, consists at present of three principal parts, viz.: an air reservoir, a earbureter, and a thermo-tracer.
The air reservoir consists of an iron plate cylinder, (I (Fig. 1), which enters an annular receptacle, A B, so as to lighten the apparatus. This cylinder, which is lifted in order to fill it with air, contains enough of the latter to last for an hour's work. It suffices, then, to raise it once per hour, an operation that may be per formed without much labor. While it is being raised, the air eaters through the valve, E. The
cylinder descends by its own weight and exerts upon the air a pressure that may be made to vary within certain limits by charging the cylinder with weights that vary in heaviness according as it is desired to give the thermo-tracer a more or less elevated temperature.
The air compressed by the cylinder escapes through the tube, J (Fig. 1, No. 2), and divides into two parts. One of these enters the carbu reter, 1) (which consists of a vessel containing a sponge saturated with a hydro-carburet—alcohol, wood, naphtha, benzine. etc.), makes its exit at and reaches the thermo-tracer through a very flexible rubber tube. The other portion of the air flows directly to the tracer, in order to keep its handle cool. To this effect the thermo-tracer is provided with a hollow wooden handle, around which circulates the air forced directly by the reservoir, and the discharge of which is regulated by a cock situated above the earbureter, so as to prevent waste, and yet at the same time to assure sufficient cooling. The thermo-tracer is a simple metallic tube, to which is screwed the platinum tube, II, raised to incandescence. The enlarged part contains an aperture through which escape the products of combustion, which latter takes place at the pointed extremity of the platinum tube.
Tracers of varying sizes and contours can he screwed on. according to the nature of the work to be done, and the effects produced may thus be varied.