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T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERIA-G C H E M I S T R Y
These rules represent a material progress made in the gradual elimination of deception and fraud which has been in pTactice, without restraint, for many years. During recent years, with the great influx of newer remedies, there has appeared in the European and American markets, a large number of preparations, so named and labeled a s to suggest either their therapeutic action, or similarity to other established true synthetics. These preparations, being mechanical mixtures of well-known therapeutic agents, are therefore calculated to deceive the medical profession, and considering the persistence with which they are pushed, i t is high time that concerted action be taken by chemists, physicians and pharmacists on both sides of the Atlantic, in order to control this nuisance. V. COBLENTZ.
QUOTATIONS. THE OXIDATION O F ATMOSPHERIC NITROGEN. By DR.
OTTO S C H N E I D E R .
(Lecture delivered before the Verein Deutscher Chemiker, 1908; Authorized translation-Extracts.)
I n the process of the Badische Anilin & Soda Fabrik, electric arcs produced by powerful currents and of a length never before attained are used. But these arcs burn very quietly, and special care is taken to displace them as little as possible by the motion of the air by causing the air to flow along the arc in the direction of its length. This way is so entirely different from the traditional one that there was no lack of dissenting voices who called in question the practical utility of our method, and curiously enough, by giving diametrically opposite reasons. Some said that this method of conducting the air did not allow i t to come sufficiently in contact with the arc, while others claimed that i t remained in contact too long. Well, in the meantime we have demonstrated that our process can compete successfully with any other, The principle of the process consists, as we have already indicated, in conducting the gases to be acted upon along a quietly burning electric arc of great length, in surrounding, as i t were, the electric arc with an advancing mantle of gas. The apparatus with which the operation is conducted is as simple as the principle itself. It consists essentially of a tube in the axis of which the electric arc is quietly burning surrounded by a mantle of the gases which are to be combined. The tube itself and the motion of the air in i t must be so arranged that any one-sided motion in the direction of the arc is avoided as perfectly as possible, while i t does no harm if the air comes from two opposite sources or is introduced towards the arc through a slit with equal pressure from all directions a t once because this does not disturb the position of the arc. Now, there is one kind of motion which satisfies this condition part'cularly well. For this reason we have used i t almost exclusively in our method on a large scale. It enables us to obtain arcs of enormous length, which a t the same time are so stable that they can burn for weeks without having to be relighted. This is a motion of the air which in spite of the greatest rapidity permits that portion of the column to remain a t rest in which the arc is situated. This kind of motion is familiar to you all, it is the spiral or vortex motion. You all know with what devastating power cyclones visit certain regions of the earth with terrifying regularity.
They move like a solid mass across the country for miles laying low everything before them. Nothing is able to withstand the impact of this whirling air and yet they carry in their centre a region of calm. We have utilized this phenomenon. We generate such a vortex in miniature in our tubes and in its calm centre we maintain our electric arc. The particles of the air rush along the arc in a rapid screw-like motion and are combined in the desired way. I n this way electric arcs of almost any desired length may be kept burning quietly. The tube may be made of any material. We take for example an ordinary iron gas-pipe. An electrode insulated from the pipe is attached on the inside a t one end and the air is introduced at this end. The insulated electrode is connected with one pole of a high tension current and the pipe itself with the other pole. The whirling motion of the air is produced in the simplest possible manner by tangential introduction. The arc is then lighted in any desired way. I will not mention the different ways in which this can be done, as they are well known to every electrician. It is immaterial which way is chosen in our process, because, as we have already stated, the arc when once lighted can be maintained for weeks without relighting, I n the simplest form the arc may be started by making the distance between the pipe and the electrode so small that i t will be overcome by the tension of the interrupted circuit. As every electric arc must be provided with an inductive resistance which is indispensable to produce quiet burning and which is present in every ordinary alternating current arc lamp, the tension between the electrode and the pipe is diminished by a certain amount as soon as the arc is lighted and with this diminished tension the current will not jump across again as long as the arc continues to burn. If i t should go out for any reason, a new arc will be formed of itself because of the renewed increase in the tension. With this method of forming the arc the air enters the tube below the electrode and pushes one end of the arc, which is quite short a t first, rapidly before i t along the wall of the pipe. As soon as stability is reached, which comes to pass so quickly that the eye is hardly able to follow the process, the result is an arc which burns quietly in the axis of the pipe, its end being far from the electrode attached to the centre. This end is a t that point of the wall of the pipe where the gases have become so hot as to acquire sufficient conductivity for the current to jump across them. The location of this point depends entirely on the conditions adopted. Of course the place where the arc terminates must be cooled off by means of water or in some other suitable way. The method of starting the arc which has just been described requires a very narrow space between the pipe and the electrode. A certain pressure is used to make the air which is introduced pass through the narrow space. This inconvenience is avoided by introducing the greater part of the air above the electrode, or by increasing the space, and producing in some way a brief temporary short circuit between the pipe and the electrode, as for example by means of a rod introduced from the outside, or an induction spark or a slender flame and the like. I t does not matter because the arc when once lighted properly keeps on burning quietly, as has been stated, without going out. The tube may also be made of non-conducting material, such as fire-clay for example. I n that case the arc must be
T H E JOURA'AL OF I N D U S T R I A L A N D E N G I N E E R I N G CHE.\ldISTR Y . started b y a temporary approach of the second electrode or by the use of a conductor along the wall of the tube to bridge over the space between the electrodes. You see here three small furnaces with glass tubes constructed to illustrate the lecture. I n two of these tubes there is placed a wire wound spirally and connected with the upper metallic post of the apparatus which forms the second electrode. The object of using the spiral form is to make the wire lie fimly against the wall of the tube. At the lower end this wire is separated b y a very small space from the electrode situated in the axis of the tube, so that an arc may be formed there in consequence of the tension existing in the circuit. This apparatus illustrates the case where the tube is made of metal. \Ye may imagine that the wire is all that is left of an original entire wall of metal. If the apparatus were entirely of metal you would not be able to see the rapid upward course of the electric arc. I now admit the air with a certain velocity through a tangential attachment below the spot where the electrode and the wire are separated b y a short distance and connect the lower electrode with a high tension current. You will immediately see one end of the arc climb up along the wire and as a result an elongated arc burning quietly like a candle or a gas flame. And it is, in fact, a gas flame that you see, i t is burning nitrogen. The arc proper, that is to say, that portion in which the electric current chiefly passes, is much slimmer than what you see-a fact which can be shown by passing a single gas, for example nitrogen alone, through the apparatus. The slight irregularity in the shape of the arc is due to the fact that the air flows through the tube with a simple screw motion. If the air were admitted through several openings or uniformly through the whole circumference, the arc would form a perfectly straight line. Please observe that the arc does not touch the wire while burning, but only when i t is start 4. I n the .ther apparatus there is no wire inside the tube. Here I must start the arc by bridging the distance between the two electrodes b y momentarily connecting them with a s i r e . The arcs in the small apparatus consume about 4 amperes a t 3000 volts or in round numbers 16 h. p. of electric energy. You see the resulting product in the flasks of the apparatus in the form of a yellowish brown vapor. As is well known, the fist product in the electric arc is colorless nitrogen oxide which then oxidizes further to NO, on cooling in consequence of the excess of oxygen present. I n maufacturing on a large scale these nitrous gases are first used for heating steam boilers and when they have been cooled in this way they are passed through percolating towers with water, where they are converted into nitric acid which is used to dissolve limestone. I n this way a solution of calcium nitrate is obtained which is evaporated in a vacuum b y means of steam. This lime saltpetre is equal to Chile saltpetre in every respect as a fertilizer and even superior to i t for soils poor in lime. After the details of our furnaces had been tested in the years I905 to IgOj in Ludwigshafen, we started an experimental factory of 2000 h. p. last autumn in Christianssand, South Norway, in order to test our furnaces b y long-continued operation. Three furnaces are now- in continuous operation in Christianssand. The length of the flame is about 5 meters and their energy about 600 h. p. We have run one furnace temporarily with 700 kilowatts or approxi-
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mately 1000 h . p. These enormous electric arcs are kept burning just as easily and surely as the much smaller ones I have shown you here. This is the more surprising when we consider that an alternating current of 50 periods is equalized in them, that is to say, that the current ceases IOO times per second when it passes zero and then flows through its long path again in the opposite direction without requiring the arc to be relighted. These manufacturing furnaces, to be sure, look rather different from the lecture apparatus exhibited here. I n them the air is systematically heated by the hot discharge gases to about j O O o C. before its entrance in the electrode pipe proper. The principle, however, is the same after all. To obtain a good result the pipes must have the right dimensions, the air must be supplied uniformly and the upper part must be well cooled. All this is easily accomplished in our furnaces, as you see. These furnaces are very durable. The only part subject to more rapid wear is the lower electrode and this we cool specially with water in our industrial furnaces. I n its simplest form, as in the lecture apparatus before us, it may consist of an iron rod which may be moved forward for adjustment, but other materials may also be used for electrodes. Conductors of the second class, as for example zirkon oxide, may also be employed. Our process differs from all other known methods b y its excellent utilization of the electric energy and a t the same time b y yielding a gas of relatively high concentration which essentially facilitates absorption. The appaiatus is extremely simple and cheap. There are no movable parts, expensive magnets or the like, and as the arc burns quietly the factor of electric efficiency is high. I t will not be long before saltpeter factories will spring up wherever circumstances permit. I suppose i t is generally known that we have combined with the owners of the Birkeland-Eyde process in order to work together. For this purpose factories with 1 2 0 , 0 0 0 h. p. are in process of construction in Sorway. I t is true that the new industry is limited by the presence of very cheap sources of power, but for this very reason i t is doing pioneer service by opening to industry regions which might have remained dormant for many decades if i t had not been for the sudden demand for great quantities of cheap energy.
THE PRODUCTS OF THE BADISCHE ANILINSODA-FABRIK.
AND
(From The Badischc Book, 1908.)
The enormous progress and changes which have taken place in the course of the past century in industry and commerce, are due, to a great extent a t least, to the utilization of the energy stored up in coal. * * * Chemical science and the a r t of the manufacturer have succeeded in producing from coal an unlimited series of valuable dyes, and b y this meansh ave brought into existence a flourishing industry. It is but little more than thirty years ago that dyers were entirely dependent upon the so-called natural coloring matter obtained from plants and animals, or prepared from minerals, from metals or from earths. The introduction of dyes derived from coal tar led to a complete change in the dyeing industry. * * * This brilliant success must be attributed
