I am constrained to dissent from the judgment of the court holding the Langmuir patent No. 1,558,436 valid. I have the same trouble that other tribunals have had throughout the twelve years of the patent prosecution and five years of the patent’s life in finding precisely what Langmuir invented. My trouble, like that of others, has been increased by the difficulty which attorneys for. the patent have had in defining the invention and by the difference between their definitions and the claims of the patent.
This is more than a mental disturbance, for manifestly a patent to be valid must relate to some invéntion, something patentably new and useful, and must disclose the invention so that a court, looking through the eyes of those skilled in the aft, can see what it is.
The art — really two related arts — is that of wire and wireless telephony, the latter commonly called radio. The invention relates generally to an electron discharge device comprising the familiar vacuum tube in which the customary electric current is carried by negative charges called electrons from the cathode to the anode, sometimes associated with a grid, and relates particularly to a vacuum space so free from gases as to avoid ionization. If the parts and principles of the mechanical construction were new and the gas evacuation old, there might be invention; and also if the structure and its principles were old and the gas evacuation- — high vacuum — were new, still there might be invention. But the essential parts and principles of the mechanism, comprising a tube, cathode, anode and grid, were old, and high vacuum in the tube also was old. So the inventor was forced to admit the presence of these old elements, yet, still insisting he had created something new, he was compelled to avoid the common art terms applicable to these elements and particularly that of “high vacuum” in disclosing his invention and use technical terms which, as I understand them, mean the same old things. With this necessarily general preface to a highly complicated situation arising out of a difficult art, I come to the matters in hand.
In an effort to find what Langmuir inventéd, it is well to begin at the beginning. I shall therefore turn to his application for a patent, for in that instrument must appear the substance of the invention as the basis for subsequent amendments and for the patent as it -eventually matured.
A recital of the prosecution of a patent application through the Patent Office is dreary reading yet, in this instance, it shows quite clearly that even the applicant was far from certain what he had invented. , Naturally I hesitate to say this about Irving Langmuir, a great physicist, yet, saying it with entire respect, I am convinced that the history of the' application establishes that fact and therefore is pertinent to the ever present inquiry: What did Langmuir invent?
The patent issued on October 20, 1925. The application was filed on October 16, 1913; renewed March 14, 1916. These, are critical dates. The original application contained five claims; two for process of removing ionizable gas from vacuum electron discharge devices, that is, in plain words, for obtaining a high vacuum, and three for methods of preparing such devices, and no claims for discharge devices themselves. The specification conformed to these claims, referred to the art, stated the problem, disclosed construction adapted to the operative principle of such tubes and showed how they can be “evacuated” of gases by heating the glass walls, heating and bombarding the metal parts,» thereby expelling occluded gases, and drawing off both free gases and expelled gases' “by a suitable evacuating means, for example, a Gaede molecular pump.”
"It should be noted that when the application was filed in 1913 the radio art was in its infancy but that, in 1925, when the patent issued, the art had attained an amazing growth. It is pertinent to inquire what happened to the application during this span of twelve years during which the mysteries that had enveloped the early art were largely dispelled and replaced by' a broad knowledge of its principles.
After the application was filed in 1913 it lay practically dormant for several years, the applicant filing enough amendments by additions and cancellations to keep it alive. Amendments to the specification occurred as follows: Two in 1913; eight in 1914; one in 1915; five in 1916; three in-1917; three in 1919 and forty-five in 1925, the year the patent issued.
Amended claims were filed and additions thereto and cancellations thereof made as follows: Four in 1913; fifteen in 1914; twenty in 1916; five in 1917; nine, in 1919; five in 1921 and forty-two in 1925, the year of the patent.
Analyzing these amendments, it appears that the five original claims (which were for *939process and method) were at different times wholly canceled. Late in the year 1913 Langmuir first made claim to invention of a structure or device, that is, to invention of a tube. This he did by four claims. The first was amended four times and cancelled in 1925. The second also was amended four times and cancelled in 1925. The third was amended four times and was not cancelled. The fourth was amended once and cancelled in 1925. Of the thirty-two claims allowed in the issued patent, four are for method and process, being amplifications of the original method and process claims cancelled; twenty-eight are for a device. Of these device claims one was filed by amendment in 1913; one in 1917; nine in 1919; three in 1921 and fourteen in 1925, the year the patent issued. Bearing on the question whether Langmuir knew and disclosed in 1913, or indeed in succeeding years, what he had invented, it is significant to note that during! twelve years, and mainly in the latter part of that period when the art had grown and reached a high stature, he rewrote, by sixty-seven amendments, the major part of his specification and cancelled all the original method and process claims and by one hundred amendments added, changed and cancelled claims until finally he was allowed the thirty-two claims of which twenty-eight, the claims for a device, are entirely new. It would he instructive, yet impossible within the permissible bounds of an opinion, to trace the progressive changes from the method and process claims of the original application to the device claims of the matured patent. But device claims having been allowed, they inevitably bring into the ease certain devices of the prior art of which two are presently pertinent.
Long before Langmuir applied for a patent, Fleming, an English inventor, brought into a very feeble art a practical electron discharge device, comprising a cathode and anode in a vacuum tube. Also long before Langmuir’s application, De Forest improved on Fleming by producing an electron discharge tube which he described ¡is an oscillation detector and called an “audion.” The improvement consisted in adding a grid to Fleming’s elements. The construction and functions of both devices are given in an elementary way in the opinion in Westinghouse Electric & Mfg. Co. v. De Forest Radio T. & T. Co. (C. C. A.) 21 F.(2d) 918, 919. The audion as conceived by Fleming and improved by De Forest at once became and has ever since continued to be the basis of the modern art of transmitting sounds great distances both by wire and through the airv Just here dates are important. A patent for the audion (No. 879,932) issued to De Forest in 3908. The audion vacuum tube was therefore in existence and its principles of operation presumably known by Langmuir when in 1913 he filed his application for a method of evacuating such a tube, although he had not seen one until that year. In 1912 or 1913, the American Telephone & Telegraph Company, committed to the operation of transcontinental telephony by the opening of the San Francisco Fair, acquired rights under the De Forest patent and, first exhausting the gas and heightening its vacuum, used the De Forest audion as an amplifying telephone relay, thus making possible the first transmission of vocal words from coast to coast by wire. In 1917 the De Forest Radio Telephone Company, assignee of the De Forest patent, granted (with certain rights reserved) a license to the Western Electric Company to make, use and sell the invention for certain purposes with the right to grant sub-licenses. In 1920 the General Electric Company, the plaintiff in this' suit and the assignee of the Langmuir patent in suit, acquired through mesne conveyances a sub-license to make, use and sell the De Forest audion, De Forest Radio T. & T. Co. v. Radio Corporation of America (C. C. A.) 20 F.(2d) 598, 599, 600, which’(probably with a heightened vacuum) it did on a vast scale until the De Forest patent expired in 1925, the year in which the patent in suit, after twelve years of travail in the Patent Office, issued to Langmuir, assignor to the General Electric Company, for an electron discharge tube including the essential parts and now universally accepted principles of the Fleming-De Forest tube. The Langmuir patent now completely covers the field previously occupied by the audion of the expired De Forest patent, and will, on the decree of this court, continue to cover it for twelve years more; hence the importance of this litigation.
Turning to the patent as it issued, the specification must first be looked at, for it contains some references to the behavior of electricity in a vacuum tube, old and well known, which are necessary to an understanding of the case. First there is a description by words and diagrams of mechanism for a vacuum tube. If new, this, it would seem, is unimportant as the specific mechanism is not claimed. Its importance resides in the fact that the patented device comprises the three elements of the general mechanism *940found in the art — the cathode, anode and grid, variously positioned in a vacuum tube to get the best electrical result — and in the fact that, as I read the record, these three elements, separately and in combination, operate on the same principle in which they operated in the art. Describing their operation, as the art then knew it, Langmuir said:
“The passage of an electric current across a tube ordinarily involves the movement of negative charges called electrons which, under the influence of the impressed voltage, pass from the cathode to the anode through the vacuous space. If these electrons when moving above a certain velocity collide with gas molecules they tend to ionize the molecules, splitting them up into electrons and larger and more slowly moving ions. Under these circumstances the phenomena of conduction across the tubes are the result of the action and interaction of electrons and the ions; * * * The cathode under these conditions is disintegrated, * * * which causes its rapid destruction. * * * The bombardment of the cathode by positive ions also causes heating of the cathode. The ionization of gases at low pressures by collision with electrons occurs at definitely determinable voltages, these voltages being known as the ionization voltages. * * * (It should, for later use, be noted here that Langmuir said nothing about gas being a supposed medium for conducting electrons from one electrode to the other.)
“If for a given cathode temperature the voltage is sufficiently high to cause all the electrons emitted or liberated at the cathode to be drawn away, then a further increase in voltage produces substantially no change in the current. The current thus determined is called the saturation current, and the range of operation in which the current is substantially independent of the voltage or approaches this condition may be called the saturation range or more briefly designated merely as saturation. If for a given cathode temperature the voltage is not high enough to cause all of the electrons which are emitted or liberated at the cathode to be drawn away, the operation occurs in a range below the saturation range.. Operation in this range may be spoken of as operation below saturation.”
Predicated on these two definitions of ionization and saturation Langmuir by claim 2, which has been treated in this litigation as a typical claim, said that his invention is:
“A discharge tube having a cathode adapted to emit electrons and an anode adapted to receive said emitted electrons, the tube walls being fashioned or shaped to permit the direct passage of a useful proportion of said electrons from cathode to anode, the gas content or residue of said tube and the relation of the parts of the tube being such that the tube is capable of being so operated in a range below saturation and materially above ionization voltages that the space current is governed or limited by the electric field of said electrons substantially unaffected by positive ionization.”
That, as I read it, simply means “high vacuum,” for a tube properly fashioned and shaped by skilled workers and highly (thoroughly) evacuated of gases — free and occluded — will in conjunction with a two electron group or with a group of two electrons and a grid produce ' these results; both groups, then and now, being in common use for different purposes by the art and by the plaintiff itself. '
For the purposes of this ease, vacuum means gas evacuation, high vacuum means vacuum above the ionization point, and, by the 'same token, a high vacuum tube means a non-gaseous tube. If the language of the claims means high vacuum, it is prior art, for the art was entirely familiar with the fact and effect of such a vacuum; and if prior art, Langmuir invented nothing.
When the patent came into litigation in this ease in the District Court of the United States for the District of Delaware the learned trial judge, having trouble with the claims, endeavored to get from the plaintiff eC definition of the invention, asking time and again, as did this court on appeal: If not high vacuum, what is the invention? An answer to this question seemingly had its difficulties. The plaintiff, of course, could not say that the invention was high vacuum alone, or high vacuum in combination with Fleming andDe Forest parts alone, for that would be an-admission of old art and would instantly avoid--th? patent. It was forced to admit that the Langmuir device included all these old elements but claimed it included “something else.” So, eventually, in order to show this something else — something new — it produced, under the insistence of the trial court, this carefully constructed definition of Langmuir’s invention, on which the case was tried below and on which it was first argued and decided in this court on appeal:
“The Langmuir invention is a coordination of elements having a new functional relation between various factors, producing a *941new result. It is not a matter merely of maintaining a certain vacuum, far less of producing a. certain vacuum which will be destroyed the moment the tube begins to operate. It involves primarily a relation between the shape, size and space relation or “geometry” of the parts of the tube and the nature and pressure of the gas therein contained, coordinated and adjusted with respect to the conditions of the electric circuit.”
That, I surmise, would be a bad patent claim. However, as it was intended to describe the invention more clearly and more definitely than Langmuir had disclosed it in the patent claims I shall take it as it is written and try to find what it means. I discern in its generalization three factors: (1) Gas pressure in the tube; (2) “shape, size and space relation or geometry of the parts of the tube”; and (3) the relation of one to the other.
The first factor of gas pressure, or, more properly, the lack of it, if it means anything, must mean a minimum of gas. This in turn means high vacuum. If it does not mean high vaeuum there is no new vaeuum factor of invention in the device, for low vaeuum was old and that is an end to the case. If it does mean high vacuum then again it is not new, for high vacua, their uses and effect and how to produce them, were long known and practiced in the art.
The second factor, or “geometry,” of the physical tube elements is not, so far as the claims reveal, involved in the invention. The physical elements themselves were old. This the plaintiff admits. Though differing in shape from some others, they are not claimed to be inventively novel in themselves. Indeed, each claim describes the invention not so much by its parts as by its characteristics of operation and results — characteristics inherent in any electron discharge tube possessing a high vacuum. Nor was this an inadvertence for when the Examiner, on rejecting certain device claims on prior art references, said:
“If applicant’s device is an improvement over the reference he should define the difference by structural limitations,” the applicant (Langmuir) replied by saying:
“The ‘structural limitations’ in this case are to be found in the difference of vacuum.”
So, thus far, the invention, with old parts and a high vaeuum, gets back to the question whether there was invention in the “difference” between low vaeuum and high vacuum, a difference existing in and known to the art.
The third factor, the relation of the two factors of gas pressure and physical parts, appears nowhere in the claim unless it be implicit in the words “the gas content or residue of said tube and the relation of the parts of the tube being such” as to produce a certain result. (Gas pressure is scarcely a part of a tube.) If it is so implied, Langmuir cannot claim invention by implication. The claim therefore is void for inadequate disclosure. If it is not so implied, there is no claim for the third factor.
Whether I am right or wrong in this analysis of the plaintiff’s statement of Langmuir’s invention or in my disposition of its elements is not important for the validity of the patent depends not on the plaintiff’s conception and definition of the invention but on the claims of the patent.
So I come back to the claims of the Langmuir patent to find Langmuir’s invention. But before doing that I am arrested by still another entirely new definition of Langmuir’s invention, this time made by the court in its opinion. The court did not adopt the plaintiff’s definition of co-ordinating elements with functional relations but, stating that a non-gaseous electron discharge device did not exist before Langmuir, found the invention to reside in his producing a non-gaseous tube in place of a gaseous tube of the prior art or, in other words, in substituting a high vacuum for a low vacuum, the very thing which all along the plaintiff was forced to avoid in its definition because it was old. Without conceding its predicate, I agree with the court’s succinct definition of the invention; but as the invention so- defined was old I cannot agree to hold a patent for it valid.
It now appears, and I say this with entire respect, that in interpreting and sustaining the patent broadly for a non-gaseous tube the court has given the plaintiff more than it ever dared to claim. A high vacuum or non-gaseous tube, being old, the plaintiff knew that an admission that the invention was a non-gaseous tube and nothing else would defeat the patent. Langmuir also must have known that a non-gaseous tube was old for otherwise, if he had believed he was the first to conceive and make one, he could, and doubtless would, have claimed it in a half dozen words: “A non-gaseous discharge tube,” or “an electrical discharge device with a high vacuum tube,” whereas in his original application for a patent he made no *942claim for a tube Of that kind or, indeed, for a tube of any kind, the inevitable inference being that at that time he thought all he had invented was a new method or process of gas evacuation, that is, a new way to produce an old thing. But that the plaintiff realized the necessity of claiming for the invention something more than a high vacuum tube or non-gaseous tube is evidenced by its earnest and repeated contentions that Langmuir’s invention, while including a non-gaseous tube— high vacuum — admittedly old, included “something else,” that something else being disclosed by the remainder of the long claims and interpreted in its quoted definition. The plaintiff nowhere and at nó time has claimed that Langmuir invented, a non-gaseous tube per se. And wisely so, for it well knew that, while not in universal use, non-gaseous tubes were in commercial use before Langmuir for sorbe purposes and that gas evacuations were as thorough as the instrumentalities of the art in 1913 would effect, and that was substantially above the ionization point, which is the crux of this case.
Returning to the patent claims and using claim 2 for convenience, it appears that the invention is an electron discharge tube which is capable of being operated below saturation and above ionization voltages. Langmuir called this a “pure electron discharge device” —“pure” because unaffected by gas ionization which is either entirely absent or negligible.
Electricity is an elusive subject. Therefore I shall, for the immediate purpose, restate in plain words; if I can, the theory of ionization.
Ionization is an effect produced by passing an electric current through gas which remains in a vacuum tube when it has not been thoroughly evacuated. The myriads of electrons, when passing from cathode to anode above a certain velocity, collide with and break up the molecules of gas present and charge the resultant broken parts or ions with positive charges of electricity. Thus electric reaction is inevitable. The ions (with their positive charges of electricity) fight against the electrons (with their negative charges) in the normal flow of the latter from cathode to anode resulting, at high voltages, in a blue glow which is the indication of bad action, a thing, to be avoided. The central point of this statement is that ionization occurs at certain voltages in an electron discharge tube when, not being thoroughly evacuated, it contains air or gas, whether gas free in the tube or gas occluded in its parts and liberated by heat during operation. The amount of ionization depends upon the amount of gas present. Langmuir prescribed in his specification that occluded gas should be expelled from the tube parts; from the tube by heating its glass walls; from the cold electrodes by electron bombardment — the liberation of gas by the electric discharge itself; and from the incandescent cathode by the heat of an electric current; all old; and after this, that both the expelled gas and free gas should be pumped out of the tube during the heating process (old) by “a suitable evacuating means (old) for example, a Gaede molecular pump,” then a new German invention.
Thus the capital requirement, if not the sole requirement, of Langmuir’s claimed invention, is as nearly as possible to withdraw from the tube all gas, free and occluded; in other words, to obtain as high a vacuum as possible. When that is done ionization is avoided and a pure electron discharge follows. Was this new with Langmuir?
Langmuir was met in the Patent Office with the Law Examiner’s statement that:
“It is apparent after a review of the record that there is no single element which is broadly novel in the assembláge of elements making up an electron discharge device of the character defined in the issue. An evacuated tube having therein an incandescent electron emitting cathode a/nd an anode was old •prior to the filing of Langmuir’s application, and methods of attaining high, vacua, sufficient to give a relatively pure electron discharge in a properly designed tube were also well known and available to persons skilled in the art.” ,
Was that statement of the Law Examiner correct? I think it was. Just here occurs my sharpest departure from the opinion of the court which is based, as I have before stated', on what I am constrained to believe is an erroneous theory or finding that all discharge tubes before Langmuir were gaseous and that Langmuir’s invention is a non-gaseous tube.
If that was his invention, clearly he must have been the first to conceive it and reduce it to practice. That the Examiner was right in saying that high vacua in electron discharge tubes were old before Langmuir and that a pure electron discharge — the inevitable result in a high vacuum non-gaseous tube and an impossible result in a gaseous low vacuum, tube — also was old is sustained by many prior *943publications and patents. The same prior publications and patents contradict, I think, the court’s holding that Langmuir was first to make and invent a non-gaseous tube. They are so numerous that it would not ho permissible to quote them in an opinion. I shall therefore do nothing more than cite a few of them, ranging from 1881 to 1912, found in the record and to be used by anyone who should desire to check up this statement or who may he charged with ‘the duty of retrying the issue. They are: Lilienfeld, Fleming, Doane, Von Baeyer, Bissel & Hagen, Malignani, Edison, Dwyer, Duncan, Leonard, Soddy, Thatcher, Child; illumined by the testimony of Waterman and Chaffee.
On these ref erenees I stand; and on them I would hold the patent invalid for want of invention.
Passing from the literature and patents of the prior art as affecting the validity of the patent for want of invention, I come to the question of prior use. The trial court found the patent also invalid because of prior use by De Forest on evidence as to which there is little dispute on the facts as distinguished from inferences. The test is the voltage at which ionization ordinarily oeeurs in a “gassy” tube. It is given at from 20 to 30 volts. That is not disputed; they are Langmuir’s figures.
Prior to August 1912, De Forest was the electrical engineer of the Federal Telegraph Company of California and was engaged in developing the transmission and reception of messages by radio. In this work he used his oscillation detector or audion then normally having a gas content. It was a “gassy” tube. But desiring to use it not as a detector hut as an amplifier, as later it was almost universally used and indeed as made for that use by the plaintiff itself under license and by the Westinghouse Electric & Manufacturing Company, its sub-licensee, he had the audion exhausted of gas as far as it was possible in that day. That is, he sought and obtained as high a vacuum in the tube as existing means would produce. When the vacua were too low and the amplifications poor he complained to the manufacturer and had the tubes re-exhansted. During that period (1910, 1911 and 1912) the Federal Telegraph Company used De Forest’s amplifying audion at 54 and 67½ volts. This was possible only because he had exhausted the tubes of gas, which otherwise would produce ionization at 20 to 30 volts, and thereby heightened the vacuum above that danger line. This was “high vacuum” within the definition oí vacuum above the point of ionization and was therefore high vacuum within the sense of those words as used in this case. It was not so high as that later attained by more modern means, for instance the Gaede moleeular pump, which had just come into the art at the time of the patent application, referred to by Langmuir in his application and invented not by him but by Gaede. I agree with the court that De Forest did not then understand the change in operative principle for in later years he expressed views contrary to those advanced both before and after that time. But De Forest did change the vacua of his tubes in changing their function from detectors to amplifiers. Whether he knew the principle of the change is of no consequence. The fact is he did it. And he did it before Langmuir. And by doing it he got rid of the ionization Qf low vacuum and obtained, and put into commercial practice for nearly three years before Langmuir, the very electron discharge of Langmuir’s claimed invention.
What I have said about the deviee elaims applies equally to the method and process claims.
On the subject of validity as involving invention I shall conclude this phase of the discussion by referring very briefly to the claimed advance made in the art by Langmuir’s invention, matter with which the plaintiff very earnestly began and ended discussion in its brief and at the argument and matter by which the court was impressed. Admittedly, when invention is in doubt — yet only when it is in doubt — favorable reception by the art may he placed in the scale. As the four judges who heard this ease have divided evenly on the question of invention, I shall, for that reason only, assume there is doubt as to invention. The plaintiff says that today everybody uses “the Langmuir tube,” a name given it not by the art (as the plaintiff frankly admitted at the argument) but by the plaintiff itself; that Langmuir, seeing through the mysteries of the art, made an invention that revolutionized the industry and made possible the transmission of sounds through the air for great distances which without his invention would be impossible.
Much litigation in respect to the radio art has drifted to this circuit. Oddly enough, in every case the plaintiff has claimed for his invention the whole credit for its growth. I am satisfied from the number of cases we have heard that the whole credit for the amazing advance of the radio art cannot be *944given to any one invention or even to a few <?f them. In truth, the art is the .product of innumerable impulses. The original impulse was, of course, the vacuum tube appearing years ago in the incandescent lamp. art. Another impulse given in the incandescent lamp art. and transferred to the radio art was that of the Just and Hanaman unstable squirted tungsten filament displacing Edison’s bamboo filament; still another was Coolidge’s method for obtaining a filament of pure tungsten, strong and stable. Impulses in the radio art itself pame from many inventors. At one time there were seven thousand applications for patents pending in the radio section of the Patent Office. To mention only one or two inventions, they include discharge devices of the Fleming two electrode type and the De Forest type'with a grid added to Fleming, the feedback circuit invented at different times by De Forest, Armstrong, Langmuir and Meissner. There are many more, without any one of which it has always been said by the particular inventor that the art would have gotten nowhere. And now the plaintiff here says the same of Langmuir.- Important and indeed great as some of these inventions were, no one of them is entitled to all credit for what has been accomplished in this great art, for the art has been impelled forward by’ hundreds of inventors and thousands of skilled workers. What. Langmuir claims to have done — procured pure electron discharge above ionization voltages in tubes of the De Forest type — appears to me to be the natural growth of the art, begun by others before Langmuir and by them reduced to practice with means then available, and developed to their later perfection during the twelve years of his patent .prosecution through the Patent Office.
I thought after the argument, and still think, the Langmuir patent invalid because of lack of invention and prior use. If I am wrong and the patent really involves invention, then, again, I think it invalid for, as I read the evidence, Langmuir was not the first and original inventor. On this point, to avoid repetition, I refer and subscribe to the opinion of Judge Morris holding on evidence substantially greater than the evidence in the interference proceeding that, if invention, Arnold was the first and original inventor.
And so this court, one judge dissenting, affirmed the decree of the District Court, on' its opinion, holding the Langmuir patent invalid.
In due course the plaintiff filed a petition for rehearing based on this proposition:
“In simple language, Langmuir’s invention consisted in taking out. the conductor (gas) which was in the Fleming valve and the De Forest audion and putting nothing in its place; he dispensed with what was regarded as an essential element in the operation of the tube (gas) and by doing so made a tube which worked infinitely better.”
The petition was allowed and the reargument was based on this entirely new statement of Langmuir’s invention made for the first time four years after suit was brought, five years after the patent was issued and seventeen years after the application was filed. Of course if the facts asserted were facts established by the evidence there would be no doubt, about what Langmuir did and no doubt that it was invention and, if claimed, no doubt he was entitled to a patent.
The plaintiff rests its proposition upon its own statement that “Both Fleming and De Forest depended upon the conductivity of gas as the fundamental basis of the operation of their tubes.” It makes this statement without distinguishing between detectors and amplifiers and supports it by carefully selected quotations from scientific publications in the early days of the art ranging from 1905 to 1912 (one in 1915). when scientists were feeling for the theory of electron movement in electron discharge tubes, some of whom based it on conduction by rarified gases or air, some on conduction by ionized gases, and some not on conduction at all but on free passage of electrons through space in a high vacuum, that is, in the absence of gas or air. And in addition the plaintiff to support its statement points to an adverse criticism by De Forest in 1915 of Langmuir’s “extremely high vacuum” quoted in the court’s opinion. The plaintiff ignored all the testimony on the subjects of prior art high vacua and pure electron discharge, which means absence of gas as a conductor, their advantages and uses, to which I have previously alluded with citations.
Of course, if the belief and practice of the art were that gas conducts the electrons, that gas therefore is necessary to conduction and Langmuir discovered it to be wrong, that in fact gas is an enemy to conduction, and omitted gas as an element in his tube yet obtained the same or a better result, clearly he made an invention. These are the things which now the plaintiff and also the court say he did. But Langmuir did not say so. If that was his invention he should have disclosed it in his claims for we are called upon to judge the patent on Langmuir’s disclosures, not on the *945plaintiff’s definitions of Ms invention. To be sure, be did refer in his specification to several tubes — the Geissler tube and the Roentgen X-Ray tube — “whose operation depends upon gas ionization.” He might, more or less correctly, have added to the list detectors with gas content, then and now in common use for certain purposes, whose usefulness depends on their sensitiveness and their sensitiveness on gas content. But he nowhere said in his patent that before his invention electron discharge tubes used for amplifying purposes in order more faithfully to reproduce sounds (one of the purposes of the De Forest audion and the thing we are dealing with in this ease) depended on low vacuum or that the art regarded, as an essential element of such a device, gas as a conductor, for he probably knew the contrary was true. To show that the plaintiff’s last definition of Langmuir’s invention is without foundation in the evidence I refer to, but shall not repeat, what I have said about prior knowledge and prior use of high vacuum tubes. I shall endeavor, very briefly, to show that Langmuir by Ms own words contradicts the plaintiff’s last definition of Ms invention and refutes the theory on which the court has in part based its judgment.
In Langmuir’s original specification he stated that when there was enough gas in the tube to become ionized by the discharge of electrons “The positive ions (gas molecules) take part in the conduction of current, giving at first erratic readings on measuring instruments connected in circuit,” which is what the plaintiff now says. Continuing, he said, that the audion, the De Forest tube, was a device that took advantage of that phenomenon. But he cancelled the quoted statement before the patent issued. At the trial he was examined with respect to that statement in his patent application and was asked whether the sentence would be true if it read: “The positive ions take part in the conduction of current by acting as conductors or carriers of current.” He answered: “In my opinion the sentence would have no sensible meaning if the word ‘conductor’ was left in for it is inconceivable that ions could be conductors of current. I will, therefore, confine myself to the ease where the positive ions act as ‘carriers.’ With this correction I can say that the statement would not have been true.”
With this cancellation and explanation Langmuir rested. Neither by amendment nor in Ms testimony did be again advert to a prior art theory of gas conduction which the plaintiff now says “was regarded (by the art) as an essential element of the operation.”
In the interference proceeding Langmuir testified with respect to the early work of Lilienfeld, as follows:
“Lilienfeld proved beyond question, I think, that he obtained discharges, in some eases at least, in which the effects that he measured were not dependent upon gas ionir zation. ■* * *
“Lilienfeld probably succeeded in obtaining a discharge high vacuum substantially free from effects of positive ionization in the device be described in bis 1910 paper. * * *
“Lilienfeld in his experiments of 1910 heated the walls of the vessel, he reduces the gets pressure to a low value, and in some of Ms experiments he he&ted his electrodes by electronic bombardment. * * *
“Seating of glass and electrodes, and exhaustion to low pyressure, are elements which were used by Lilienfeld and were known prior to Lilienfeld’s article. * * *
“Factor No. 1 which I gave in answer to XQ84, viz., that the bulb should be heated during exhaust to a temperature materially higher than the operating temperature, was-used by Lilienfeld in much of Ms work. * # *
“Factor No. 4, which is that which I gave in the first part of my answer to XQ87, refers to the lowering of the pressure to such a point that a further lowering brings about no further change. In many of Lilienfeld’s experiments, this condition mass realized.”
Yon Baeyer stated as early as 1909 that his “experiments were of course carried out in the highest possible vacuum to avoid the influence of ionization.” Langmuir admitted that “Wehnelt claimed that * * * cur_ rents of the order of 10 milliamperes could be obtained even in the highest vacuum.”
Referring to an interview with Richardson in 1912 Langmuir said:
“Richardson * * * expressed himself as confident that even in the highest vacuum thermionic currents could still be obtained.”'
Langmuir admitted in the interference proceeding that “prior to 1912 (the year before his application) there were some experimenters who took precautions to remove gases from the walls, from vessels and from electrodes.”
This, I think, shows that the reargument, based on an incorrect premise, should leave undisturbed the court’s first finding that the patent is invalid.
*946The plaintiff, however, prevailed. The court reversed its previous decision and will now enter a decree holding the patent valid. Erom the opinion announcing its judgment, in so far as it will reverse the decree of the District Court on the first (Langmuir) patent in suit, I dissent.
This is a long dissenting opinion. In view of the gravity of the court’s decision and its effect upon the art I make no apology for its length. I frankly admit that it is written with the hope that it will arrest the attention of the reviewing court.