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British Liquid Air Company Ld. v. British Oxygen Company Ld.

“mixture to a partial vacuum and to contact with one side of a vessel to the "other side of which is applied the temperature of air in process of precipi"tating liquid, whereby an atmosphere poor in oxygen is volatilized from the "said liquid mixture of oxygen and nitrogen, substantially as set forth. 3. "The process of treating air in order to produce from it a liquid rich in oxygen, 5 "which consists in chilling it until liquefaction occurs, in transferring the "resulting liquid to a chamber, in exposing it to a slightly lower pressure and "to contact with one side of a vessel to the other side of which is applied the temperature of air in process of precipitating liquid, whereby an atmosphere poor in oxygen is volatilized, and in causing the incoming air to traverse a 10 "counter current system to which is applied the chilling effect of the back flow "of gas poor in oxygen, volatilized from the liquid in process of enrichment, substantially as and for the purposes shown and described. 4. The process of "treating air in order to produce from it a liquid rich in oxygen which consists "in cooling it until liquefaction of a portion only of its total gaseous contents 15 occurs, whereby a liquid richer in oxygen than is air is precipitated from said "air, in transferring the resulting liquid to a chamber, and in exposing it to a 66 pressure, less than that under which it was condensed, and to contact with 66 one side of a vessel to the other side of which is applied the temperature of "the incoming air in process of partial liquefaction, whereby an atmosphere 20 "comparatively poor in oxygen is volatilized from the liquid in process of "enrichment, substantially as set forth. 5. The process of treating air in order "to obtain from it an atmosphere rich in oxygen, which consists in chilling it "at ordinary pressures until liquefaction occurs, in transferring the resulting liquid to a chamber and exposing it to a partial vacuum, and to contact with 25 one side of a vessel to the other side of which is applied the temperature of an "incoming air in process of precipitating liquid, whereby an atmosphere poor "in oxygen is volatilized in the said chamber, in transferring the concentrated 66 liquid to a second chamber, and in volatilizing it in whole or in part from said "second chamber, whereby is generated an atmosphere rich in oxygen, and in 30 66 causing the incoming air to traverse a counter current system, to which is "applied, by one passage or set of passages, the chilling effect of the back flow "of the gas poor in oxygen volatilized from the liquid in process of enrichment, "and, by another passage or set of passages, the chilling effect of the back flow "of the atmosphere rich in oxygen, substantially as, and for the purposes shown 35 "and described. 6. The process of treating air in order to produce from it two gaseous portions, one richer in oxygen than the other, which consists in "gradually conducting its temperature down to a point at which liquefaction "occurs from said air, in transferring said liquefaction to a chamber, in which "it exists under a pressure lower than its original one, and in thermal com- 40 "munication with the incoming air in process of precipitating liquid, whereby "an atmosphere poor in oxygen is volatilized in the said chamber, in trans"ferring the liquid after concentration to a second chamber, in which it exists "also under a lower pressure than its original one, and in thermal communication with the entering air in process of precipitating liquid, whereby an 45 "atmosphere rich in oxygen is volatilized in said second chamber, and in "gradually conducting said atmosphere, and the cold gas volatilized from the first chamber, by separate passages respectively, back to ordinary temperatures, "and in causing them collectively to restore to the system the chilling effect "which the original air abstracted during its passage downwards to the system 50 such chilling effect as is needed to make up losses due to radiation and "imperfection in the heat interchange apparatus, substantially as described. 7. The process of treating air in order to produce from it an atmosphere rich "in oxygen which consists in chilling it until liquefaction of a portion only of its total gaseous contents occurs, whereby a liquid richer in oxygen than is air 55 precipitated from said air, in transferring the resulting liquid to a chamber in

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British Liquid Air Company Ld. v. British Oxygen Company Ld.

"which it exists under a lower pressure than that under which it was con"densed and in thermal communication with the incoming air, in process of "partial liquefaction whereby an atmosphere comparatively poor in oxygen is "volatilized from the liquid in process of enrichment, in transferring the 5 "concentrated liquid to a second chamber, and in volatilizing it in whole or in "part from said second chamber, whereby is generated an atmosphere rich in oxygen, and in causing the incoming air to traverse a counter current system "to which are applied (by the same or by separate passages) the chilling effects "of the back flow of the gases poor in oxygen from the first chamber and from 10" the uncondensed portion of the entering air respectively, and to which is also "applied, by another passage, or set of passages, the chilling effect of the back "flow of the atmosphere rich in oxygen, substantially as set forth. 8. The process of treating air in order to produce from it an atmosphere rich in "oxygen, and a liquid still richer in that element, which consists in chilling it 15" until liquefaction occurs, in transferring the resulting liquid to a chamber in "which it exists under a lower pressure than that under which liquefaction

"occurred, and in thermal communication with the entering air, whereby an "atmosphere poor in oxygen is volatilized from said air, in transferring the "comparatively concentrated liquid to a second chamber, in volatilizing a 20" portion of said liquid from said second chamber, whereby the required "atmosphere rich in oxygen volatilized from said liquid and the required "liquid still richer in oxygen remains behind in the second chamber, and in "causing the incoming air to traverse a counter current system to which is "applied the chilling effect of the back flow of the gas poor in oxygen vola25 "tilized from the liquid in process of enrichment, and, by a separate passage, or set of passages, the chilling effect of the back flow of the atmosphere rich "in oxygen, substantially as described. 9. In an apparatus for causing con"centration, in a liquid mixture containing components of different volatility, "of the less volatile component which operates by boiling off from said liquid 30 "a gaseous mixture rich in the more volatile compound, the process of per"mitting movement of the liquid, in the act of becoming concentrated, only in "the opposite direction to that of the vapour boiled away from the said liquid, "substantially as and for the purposes shown and described."

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British Liquid Air Company Ld. v. British Oxygen Company Ld.

The Drawing given below is the diagrammatic Drawing of the Respondents' complete machine referred to in the judgment below as "X":

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During the trial the parties agreed that the matter should be dealt with as if there were a cross-action for infringement of the Patent.

It was held by Mr. Justice Warrington that the combination employed by the 5 Plaintiffs was different from that of the Defendants, and was not an infringement of the Defendants' Patent, which was held to be valid. An injunction to restrain threats and a Certificate as to the Particulars of Objections were granted, and a Certificate of validity as to the Defendants' Patent was given; and costs on the higher scale were allowed. The Defendants undertook to issue a writ to 10 restrain infringement of their Patent, and the judgment (which was given in both actions) was dated the day after the issue of that writ (25 R.P.C. 218). The Defendants in the first action appealed.

The appeal came on for hearing on the 2nd of April 1908.

Walter K.C., and J. H. Gray (instructed by Sharp and Benest) appeared for 15 the Appellants; Cripps K.C., H. Terrell K.C., and E. F. Lever (instructed by Lawrance, Webster, Messer and Taylor) appeared for the Respondents.

Walter K.C. for the Appellants.-Oxygen boils at 91° and nitrogen at 77.5°, absolute temperature. The process employed is carried out by the application of mechanical energy. Air is compressed, cooled in water, and allowed to 20 expand. [FLETCHER MOULTON L.J.-At the temperatures we have to deal with, the expansion of air under pressure produces a marked fall of tempera. ture]. Expansion doing external work always lowers the temperature; doing

British Liquid Air Company Ld. v. British Oxygen Company Ld.

no external work, it may or may not, but at very low temperatures it does. At the date of the Defendants' Patent, oxygen, nitrogen and air had been liquefied by the "cascade" method, but only as laboratory curiosities. Fractional distillation generally connotes the presence, in the liquid distilled, of bodies of different 5 boiling-points, and it, alone, is insufficient for the separation of bodies whose boiling-points closely approximate. In Linde's 1895 apparatus it is possible to obtain, even in V', as high a proportion as 46 per cent. of oxygen from air which contains 21 per cent. From 1895 to 1902 everyone proceeded on the lines of Linde, and had a repeated series of evaporations: only one person, namely, 10 Pictet, had the idea of using rectification to increase the proportion of oxygen, and he rejected it as impossible. To understand the difficulty of the problem, one may imagine the Coffey still working in a red-hot room. In Linde's 1902 apparatus the vessels s and t are covered with loose lids. The Patent is for the separation of oxygen, not for the production of liquid air. Claim 1 has been 15 infringed. The vessel s corresponds to V2 in the 1895 apparatus. The improvement in the 1902 Patent consists in the introduction of the rectifying column. As to infringement, at the time of the trial of the action nothing had been done by the Plaintiffs, but they said that the Drawing W.R. 1 showed what they proposed to do. The Drawing showed a combination of Claude's two 20 patented forms of apparatus (No. 23,682 of 1903 and No. 26,435 of 1905). The Plaintiffs have an additional boiling-off vessel. If, in W.R. 1 either of the stopcocks is shut, the apparatus is simply Linde's 1902 apparatus. Sir W. Ramsay thinks that the gases condense separately and run down; Sir J. Dewar says that the air liquefies as a whole, and that the separation takes place by 25 rectification. Claude has done something additional to what Linde did, but he cannot obtain purer oxygen than Linde obtained, and he has to expend more energy. The learned Judge below said that it was a pure question of opinion what happened in the column, and that Linde's apparatus was only for treating a mixture of oxygen and nitrogen in the proportions in which they 30 occur in air, and that if anyone used different proportions he would not be infringing. The maximum proportion of oxygen obtainable by condensation is 46 per cent. The Plaintiffs alleged that there was no subject-matter in adapting Coffey's still to the purpose of producing liquid air. The alleged anticipations Hampson of 1896, Pictet, and Le Sueur's Canadian Patent, do not deal with 35 rectification; they are all for fractional evaporation, by which pure oxygen can never be obtained. Pictet did not know how rectification was utilised; as Sir J. Dewar pointed out, if one wanted an analogue to ordinary rectification, one would have to use liquid hydrogen. Le Sueur's apparatus will not work; it has the defect of the wrong flow of the current. It is suggested that Thrupp's 40 apparatus can give more than 46 per cent. of oxygen, but it is not suggested that it has ever been worked. [Cripps K.C., stated that the Respondents relied on the Specifications of Hampson and Le Sueur.] In Le Sueur the ballcock is unnecessary; 81 is never required to be shut. It is admitted that in Thrupp and Parkinson there is no rectification. The Plaintiffs have taken all 45 the essential elements of the Defendants' invention.

Gray followed.-As to subject-matter, gaseous oxygen chemically prepared has an extensive market; Linde tried to find a cheap method of preparation. Liquid air, as such, has no market value; and Sir J. Dewar said that he had declined to associate himself with any scheme for the production of liquid air. 50 Even Linde himself, in 1895, had endeavoured to obtain liquid air by fractional evaporation, which now is admitted to be useless for the purpose-rectification is essential. But rectification is not mentioned in any of the documents, except Pictet, who warns one against it. As to infringement, the Plaintiffs have taken Linde's apparatus, and made an addition. They say that they have effected an 55 improvement by obtaining the nitrogen separately, but, even so, their apparatus may be an infringement. Air is cheap, and for the purpose of getting the

British Liquid Air Company Ld. v. British Oxygen Company Ld.

nitrogen they must supply more energy; it is questionable if there is an improvement.

Cripps K.C., for the Respondents.-If the learned Judge is right on construction, some questions dealt with need not be considered. Alternatively, so far as there is a novel element in the 1902 Patent in rectification-assuming that to be 5 novel-Claude differs from Linde in the methods and materials employed, and in the result. The cooling of the air may be brought about by the Joule-Thomson effect, or by using the air to drive a piston. Claude was the first to rely on external work; the apparatus shown in W.R. 1 operated by external work. Solvay pointed out the two methods. It is not suggested that the Plaintiffs 10 infringe the 1895 Patent. In that, in V', the Joule-Thomson effect is obtained; separation is effected by fractional boiling-off in V. In W.R. 1 nothing is going off from K but vapour, and from a liquid containing 93 per cent. of oxygen a vapour containing about 95 per cent. will go off; there is no fractional evaporation at all, while there is in both of Linde's processes. Claude first 15 succeeded in getting pure nitrogen; Linde could not get more than 14 of the 21 parts. It is said that air is cheap, and that it would not matter if one got only a very small proportion of pure oxygen; but here one is dealing with cooled, compressed air. The Plaintiffs get one-third more oxygen, and the Defendants do not get the nitrogen at all. There is an essential difference 20 between the processes, in that Claude condenses the air into substantially pure nitrogen and a liquid containing much more oxygen than ordinary air. Sir W. Ramsay was surprised to find that Claude was right. Sir J. Dewar said that one would have thought that, as one could evaporate the gases separately, one would be able to condense them separately, and 25 Claude showed that one could do that. The Claude process has been worked; the pressure used is about four atmospheres-Linde used 20 atmospheres. Claude uses external work, having found a lubricant that is effective at the low temperatures produced. There are no Particulars of a rectifying column which is quite a common device. The invention was in so 30 putting in the rectifying column as to operate effectively. The combination of apparatus is the same, but in K (of W.R. 1) there is no fractional distillation; in Linde there is fractional evaporation. It has been found that the throttle valve is an essential part of the apparatus, but the Appellants say that the finding is wrong; it is common to all the forms of apparatus to release the pressure; the 35 learned Judge does not refer to it as a matter of invention. The Respondents say that there is no subject-matter on the view put forward by the Appellants. If the invention consists in the use of the special form of rectifying column, it is not claimed; if it consists in the use of a rectifying column generally, there is no subject-matter-it has been anticipated. Any rectifying column, such as 40 Le Sueur's, is within Linde's Claim; that is for rectification-the material interchange between the vapour going up and the liquid coming down. If the Claim is construed in that way, the Respondents infringe, but there is no subject-matter. It has been held that there is a substantial difference between the two combinations. The witnesses say that Le Sueur can be worked -Mr. 45 Swinburne said it could be modified so that it would work; and Sir W. Ramsay said the method would be obvious to anyone who knew of Coffey. It is not the Respondents' view that there is a ball-cock at 9. The rectifying column in Linde is older than that in Le Sueur. Sir W. Ramsay said that Himpson's was the nearest to Le Sueur; and no one was called to say that 50. Hampson would not work. It is common knowledge that if one takes pressure off a liquid one lowers its boiling-point. The Respondents have a different combination, affecting different elements and giving different results; in their apparatus there is no fractional evaporation from beginning to end. Le Sueur's description is said to be inadequate, but anyone skilled in matters of the kind 55 could not fail to carry it out. In Hampson one has the vapour flowing upward