large preparatory heating tanks filled with naphtha to be distilled later on, which is thereby heated to between 2300 and 266° F.1 1 Engler. Erdoel von Baku. c, a, b, The lightest oils, at the utmost one-third per cent., volatilizing thereby, are condensed in special condensers connected with the covers of the tank, while the preparatorily heated naphtha is raised to the filling reservoir. From the latter, after the naphtha has cooled off to about 194° F., the first benzine still is uninterruptedly fed with the use of a regulator. The residues are discharged into large brick tanks. By the preparatory heating of the naphtha not only fuel is saved, but also sand and mud are deposited. All the stills are fired with residuum by means of Brandt's "forfunca" B (see "Utilization of crude oil and crude oil products for heating purposes later on.) The arch N protects the still from the pointed flame. The operation is carried on as follows: The first four stills, which are somewhat larger than the other fourteen, serve for separating the benzine and are, therefore, also called benzine stills, the other fourteen being the actual kerosene stills. Along the front side of the entire battery runs the principal conduit A, which is a pipe about 734 inches in diameter and a fall of one inch for the entire length. From this conduit the pipes b and c branch off in front of each still. The pipe b serves for filling the still. From the principal conduit A, the naphtha passes through the opened valve b, into the pipe b which extends to the rear end of the still and terminates in a joint pointed downward. From the still the naphtha returns through the pipe c and the opened valve c,, to the principal conduit A, to flow in a similar manner into the next still. In this case the valve at a, is always closed, so that the naphtha is forced to pass through the still. From this arrangement it will be readily understood that any still of the battery may be excluded by simply shutting the valves b, and <,, and opening the valve at a, in the principal conduit A. Distillation is effected in all stills with superheated steam, which is produced in a pipe-superheater and enters the steamspace through branch-pipes below and over the oil. The following table shows the progress of some distillations. 195 211 227 234 248 250 256 206 221 230 238 257 259 228 246 195 219 228 233 243 247 256 0.780 0.786 0.792 0.798 0.805 0.814 0.820 0.827 0.832 0.835 0.842 0.846 0.849 0.855 267 272 278 275 286 294 300 310 315 0.837 0.835 0.840 0.845 0.850 0.855 Temperature C.. 131 153 175 194 200 192 Specific gravity at 17.5° The stills Nos. 48, 49, 50, 51 are the preparatory heating stills, to which are joined the actual kerosene stills 1 to 14. In the horizontal column the temperature of a distillation and, below it, the specific gravities of the products are given. It will be seen that the distillation of Russian crude naphtha commences at 130° C (266° F.) and goes to 300° C. (572° F.), and that the specific gravity of the heaviest products used for petroleum is between 0.855 and 0.860. The result of working each still is nearly constant, the naphtha flowing through the stills yielding in each of them fractions corresponding to the temperature of the still. The difference in temperature of two adjoining stills amounts on an average to 70 or 8° C. The difference in the specific gravities is also uniform, it being between 0.007 to 0.010 degrees. Besides the general advantages of continuous distillation, the result of the operation is a greater yield, amounting to about 36 per cent.1 This greater yield is due to the large vaporizing surface which in Nobel's system is attained by the number of stills and the constantly high level. With this system of distillation the use of dephlegmators is indispensable, otherwise heavy oils may be readily carried along in consequence of the continuous supply of naphtha, the danger being especially great in the last stills. Hence the vapors of the last five stills are passed through separators, the last three stills (Nos. 12, 13 and 14 of the table) being each provided with two, one after the other, and the two preceding stills (Nos. 10 and 11 of the table) each with one. Nearly 25 per cent. of the vapors are condensed, and the heavy oil thus obtained either runs directly back into the kerosene still, or what is the usual process, is caught in a special tank and worked for lower grade solar oils. A continuously working distilling apparatus patented by Schuchow Intschik and Bary has recently been introduced in some refineries. 1 Memoiren der Kaiserl. russisch. techn. Gesellsch., 1889, Mai. EDIMENT The apparatus, Fig. 103 consists of a metallic box A which is placed upon the still B, or in its neighborhood. This box as seen from the illustration contains any desired number (generally nine) of shallow pans, which in combination with the sides FIG. 103. of the box form a series of chambers and maintain in them a constant temperature. They collect at the same time upon their surfaces the condensed vapors according to their temperature. The progress of the distillation is as follows: From the still B the vapors of the distilling fluid enter the box A, in which they circulate in the direction of the arrows and touch the surface of the pan ef filled with naphtha, thus heating the pan and consequently also the naphtha. By yielding latent heat to the pans a portion of the vapors is |