Mr. Justice Strong delivered the opinion of | der any decree made in the case, or under the the court: There are no less than twenty-seven assignments of error in this case, but the subjects of real controversy are few. The bill is an ordinary one for the foreclosure of a junior mortgage covering the canal and franchises of the Lake Superior Ship-Canal, Railroad and Iron Company, and covering also two separate bodies of land, each containing two hundred thousand acres. The mortgage was given expressly subject to two prior mortgages: one, dated July 1, 1865, upon the canal and one of the bodies of land, and the other, dated July 1, 1868, upon the canal and the other body of two hundred thousand acres of land. Each of these prior mortgages was made to secure the payment of the company's bonds of even date therewith, amounting to the sum of $500,000; and all the bonds were issued, and they are now outstanding. The first of these prior mortgages is known as the Sutherland mortgage. Default having been made in the payment of interest upon the bonds secured by that, John L. Sutherland, the trustee, filed his bill to foreclose it, making all the subsequent mortgagees parties; and they all appeared. In that case, Isaac H. Knox, was appointed receiver of all the property covered by the several mortgages, and subsequently, in order to obtain the money necessary for completing the canal, by order of the court, he was authorized to create, issue and sell certificates of indebtedness to the amount of $500,000, to be secured by a mortgage, which he was empowered to make, covering all the property, and which was to be prior in right to all other mort gages. Pursuant to this authority, the receiver did issue and sell such certificates, and for their security executed the mortgage directed by the court. These certificates are now all outstanding. Such was the condition of affairs when the present bill was filed. But the Company having afterwards gone into bankruptcy, a supplemental bill was exhibited making the assignees in bankruptcy parties defendant; and they ap. peared and made defense, and they are the only parties appellant. decree which was sought. Nor is there any doubt entertainable respecting the amount due under the prior mortgages. Indeed, the Company is estopped by the provisions of its mortgage, of which the complainant is trustee, from asserting that the entire amount of the two $500,000 mortgages, and of the receiver's mortgage, was not outstanding when the present mortgage was made. The full indebtedness was acknowledged by making the junior mortgage expressly subject to it, and as there is no evidence that any portion of it has been paid, it is not admissible for the mortgagors or their assignees_in_bankruptcy to deny it now. Bronson v. R. R. Co., 2 Wall., 283 [69 U. S., XVII., 725]. Apart from the exceptional cases, we understand the general rule to be that, in a suit by a junior mortgagee to foreclose a mortgage, prior mortgagees are not necessary parties. So it has been held in England, in Rose v. Page, 2 Sim., 471; Richards v. Cooper, 5 Beav., 304; Delabere v. Norwood, 3 Swanst., 144. Such, also, is the rule asserted in this country, where the bill of a junior mortgagee, as in this case, seeks only a foreclosure or sale of the equity of redemption. See, Edw. Parties, p. 91, and cases cited; Gihon v. W. Lead Co., 3 Halst. Ch., 531; Williamson v. Probasco, 4 Halst. Ch., 571. The subject has been under consideration by this court in Hagan v. Walker, 14 How., 37, in which it was shown that it is not necessary in all cases to make a prior mortgagee a party. And it is not easy to see why it should be in any case, when the decree asked cannot injure or affect him. In Payne v. Hook, 7 Wall., 432 [74 U. S., XIX., 262], it was said: "It can never be indispensable to make defendants of those against whom nothing is alleged, and from whom no relief is asked." See, also, French v. Shoemaker, 14 Wall., 315 [81 U. S., XX, 852]. We think this is the correct rule. It is certainly consonant with reason, and we see nothing in the present case that justifies a departure from it. We hold, therefore, that the bill is not defective for want of proper parties. The appellants next contend that the decree is erroneous, because the mortgagors were declared bankrupt after the bill was filed, and before the decree was entered; and it is urged that the Bankrupt Court had absolute and exclusive jurisdiction; and was entitled to the entire administration of the bankrupts' property. That this objection is without merit was shown in Marshall v. Knox, 16 Wall., 551 [83 U. S., XXI., 481], and Eyster v. Gaff, 91 U. S., 521 [XXIII., 403], to which we need only refer. It is now contended, on their behalf, that the bill cannot be sustained, because the prior mortgagees were not made parties. This position cannot be sustained. It is undoubtedly true there are cases to be found in which it was ruled that prior incumbrancers were necessary parties to a bill for the foreclosure of a junior mortgage, but in most of these cases the circumstances were peculiar. Where the effort of the junior mortgagee is to obtain a sale of the entire property or estate, and not merely of the equity of redemption, there is reason for making the prior A further objection insisted upon is, that while incumbrancers parties, for they have an imme- the property was in the charge of a receiver apdiate interest in the decree. And so, when there pointed in the suit brought by Sutherland to is substantial doubt respecting the amount of foreclose the first mortgage and, therefore, as it the debts due prior lien creditors, there is obvi- is said, was in custodia legis, this bill was filed ous propriety in making them parties, that the without leave of the court. If there could, under amount of the charge remaining on the land any circumstances, be any force in this objection, after the sale may be determined, and that pur- there is none now. Both suits were brought in chasers at the sale may be advised of what they the same court; these appellants appeared, anare purchasing. But the case in hand has no swered, and cross examined witnesses, and made such peculiarities. The prior mortgages were no allegation that the suit had been brought withnot due when this bill was filed; and, without out leave until about a year and a half afterthe consent of those mortgagees, nothing more wards. It was then too late. They must be held to than the equity of redemption could be sold un- | have acquiesced; and, if not, leave of the court to commence and prosecute the suit must be pre- | other mortgages objected to the order when it sumed after the orders made to facilitate its was made, though they were all then in court. progress. None of them object to its lien or its priority now. And we think the appellants, either as representatives of their assignors or of general creditors, cannot be heard to object. Beyond doubt, they would not be entitled to a return of the property discharged from liability to pay the receiver's certificates so long as they remained unpaid, even if all the other mortgages were satisfied. As against them the certificates are certainly charges upon the property, and they have, therefore, no right to complain of the decree, which gives the certificates priority to other liens. The only remaining assignments of error that require particular notice relate to the ascertainment of the liens on the property of the company anterior to the mortgage now in suit, to the determination of their relative priority, and to the adjudication of the amount of the debt for the payment of which that mortgage is a security. The court decreed not only that the two five hundred thousand dollar mortgages, one dated July 1, 1865, and the other dated July 1, 1868, are liens for the full amounts specified in them, and prior in right to the complain ants' mortgage, but that the lien of the mortgage given by the receiver appointed in the suit of Sutherland against the Company, in pursuance of the direction of the court in that case, is also a prior lien to the extent of the certificates issued by the receiver, namely: to the extent of $500,000 and interest. This portion of the decree, it is now insisted, was erroneous. But if the receiver's certificates, issued by order of the court which had the property in charge, are liens at all, what have the appellants, who stand in the place of the Company, to do with the order of priority of liens? What difference does it make to them whether the certificates be paid before any other liens are discharged, or after all the debts secured by any mortgage shall have been satisfied? The assignees can get nothing until all the liens on the assigned property have been removed. If the circuit court has made a mistake in determining in what order the incumbrances are entitled to payment, that is a matter for the consideration of the incumbrancers, in which neither the Company nor the appellants have any interest. We do not understand the appellants to contend that the entire sum of $500,000, for which the receiver's certificates were issued, is not due, or that the receiver was not authorized to make the issue and secure it by mortgage, as he did. This is admitted in the pleadings, and there is positive proof of it in the record. It would be superfluous to spend much time in considering the power of the court to confer the authority upon its receiver that it attempted to confer. As a court of equity, having the mortgaged property in charge, it was its plain duty to preserve it, not only for the benefit of the lien creditors, but also for the benefit of the Company whose pos session the court had displaced. Under the provisions of the Acts of Congress granting the lands covered by the mortgages, the lands reverted to the United States, unless the ship-canal should be finished within a fixed period, and that period was passing away when the order was granted to the receiver to raise money for completing the canal by the issue of certificates secured by his mortgage. The canal was unfinished, and there were in the receiver's hands no funds to finish it. Hence there was a necessity for making the order which the court made, a necessity, attending the administration of the trust the court had undertaken. The order was necessary, alike for the lien creditors and for the mortgagors. Whether the action of the court could make the receiver's mortgage superior in right to the mortgages which existed when it was made, it is needless to inquire. None of the creditors secured by those That all the bonds secured by the first two mortgages are outstanding and due is, we think, an established fact. We have observed that the mortgage upon which the present suit has been brought was made subject expressly to those two prior mortgages. In it the mortgagors recited that the Company did simultaneously with those mortgages, “execute, issue, negotiate and sell" all the bonds covered thereby, and declared that they were an outstanding and subsisting lien. How can these appellants, who stand in the shoes of the mortgagors, be heard to deny these recitals? Yet, if they can, we find no evidence that all those bonds are not now a subsisting debt of the Company to the full extent of the sums named in them. There is some proof that, when the Company became bankrupt (August 28, 1872), some of the bonds were held as collaterals for loans made to the Company smaller in amount than the bonds pledged. But the bonds were subsequently sold by the pledgees, and the present holders hold them by absolute right. The position that the pledgees could not sell the pledge after the adjudication in bankruptcy, is quite untenable. It is sustained by nothing in the Bankrupt Act. The bonds were negotiable instruments. They passed by delivery, and even were there no expressed stipulation in the contracts of pledge, that the pledgee might sell on default of the pledger, such a right is presumable from the nature of the transaction. Certainly the Bankrupt Act has taken away no right from a pledgee secured to him by his contract. In regard to the bonds covered by the McCarter mortgage, which is the one now in suit, we find no error in the decree of which the appellants can complain. Most of those bonds, though at first issued as collaterals for loans made to the mortgagors, have been sold, and they are now owned by the purchasers. There are some, it is true, that are still held in pledge; but the pledgees have a clear right to use them, either by sale or by collection, until the full amount of the debts due from the mortgagors is satisfied. We cannot close our eyes to the patent fact that the entire property mortgaged is insufficient to pay the debts with which it is incumbered. The holders of the bonds covered by the Union Trust Company will obtain nothing, and none of the bond holders under the McCarter mortgage will obtain full payment. At least, such is the strong probability. If, therefore, the holders of the McCarter bonds, who hold them as collaterals, are allowed to hold them only for the sums for which they have been pledged, the bonds may, and probably will, prove an insufficient security for the debts actually due from the obligors to the holders. They will prove insufficient, unless the mortgaged property shall bring at the sale enough to pay in full all the bonds held by purchasers, and also all the debts for which the pledged bonds are held. If the sale produces less, there must be a ratable abatement. On the other hand, if the pledgees are allowed to prove the bonds held by them for their full face, these appellants are not injured. If, at the sale, the mortgaged property shall bring more than sufficient to pay the debts for which the bonds are held in hypothecation, the proceeds of the sale will be under the control of the circuit court, and it will take care that a proper distribution is made. And if this were not so, the pledgees would hold any excess they might receive in trust for other incumbrancers, or for the appellants. The only persons, if any, who can possibly be injuriously affected by the decree which was made, are the absolute own ers of the McCarter bonds, and they acquiesce in it. It is not for those who are not injured to complain. Of the only other assignment of error which requires notice, it is sufficient to say, that, in view of the circumstances of the case, a sale in bulk is the only possible mode of sale which will enable purchasers to buy with confidence. And a sale by parcels, though ordinarily the proper mode, cannot be made, with any hope of justice to the creditors. The decree of the Circuit Court is affirmed. Messrs. W. S. Cox, Charles T. Blake and Rodney Mason, for appellants. Messrs. A. L. Merriman and H. C. Cady for appellees. Mr. Justice Bradley delivered the opinion of the court: This is a suit in equity, instituted in the Supreme Court of the District of Columbia for injunction and relief against an alleged infringement of various patents belonging to the complainants. The bill was dismissed and the complainants have appealed. The patents sued on are six in number, originally five, granted to the appellant Cochrane on the 13th of January, 1863, and numbered respectively 37317, 37318, 37319, 37320, and 37321. They all related to an improved method of bolting flour, the first being for the general process; and the others for improvements in the different parts of the machinery rendered necessary in carrying on the process. Three of the original patents, Nos. 37317, 37318 and 37321, were surrendered and re-issues taken in 1874, which reissues were numbered 5841, 6029, and 6030, the first being for the process, and the other two for portions of the machinery. Re-issue 6029, being in place of the original patent numbered 37321, was also subsequently surrendered, and two new re-issued patents substituted therefor, numbered 6594 and 6595. The case has been mainly argued on the question of infringement, the defendants using a bolting apparatus constructed according to letters patent issued to Edward P. Welch in April, 1873, for improvements upon machines patented to Jesse B. Wheeler and Ransom S. Reynolds, which, as well as the process employed, they contend, are radically different from the apparatus and process of Cochrane. A preliminary question is raised, with regard to the jurisdiction of the court below to hear the WILLIAM F. COCHRANE ET AL., Appts., case on a bill in equity, before a determination v. JOSIAH W. DEENER ET AL. (See S. C., 4 Otto, 780-792.) Jurisdiction-process patentable. 1. The powers of the Supreme Court of the District of Columbia in patent cases are the same as those of the Circuit Courts of the United States. Whether a patent case shall be first tried at law, is a matter of discretion and not of jurisdiction. 2. A process may be patentable,irrespective of the particular form of the instrumentalities used. A process is a mode of treatment of certain materials to produce a given result; if new and useful, it is just as patentable as is a piece of machinery. 3. Cochrane's patent for the process of bolting flour being re-issue number 5841, and the several reissued patents for combinations of mechanical devices numbered respectively 6030, 6594, and 6595, are valid patents and are infringed by Welch's patent. Cochrane's patents, numbers 37319 and 37320 are not infringed. [No. 744.] Submitted Nov. 6, 1876. Decided Mar. 19, 1877. APPEAL from the Supreme Court of the Dis trict of Columbia. The case is fully stated by the court. of the rights of the parties in an action at law. The powers of the Supreme Court of the District of Columbia in patent cases are the same as those of the Circuit Courts of the United States. See Revised Statutes, relating to the District of Columbia, secs. 760, 764. The circuit courts were first invested with equity jurisdiction in patent cases by the Act of Feb. 15, 1819 (3 Stat. at L., 481), which declared that these courts should have "Original cognizance, as well in equity as at law, of all actions, suits, controversies, and cases arising under any law of the United States, granting or confirming to authors or inventors the exclusive right to their respective writings, inventions and discoveries; and upon any bill in equity, filed by any party aggrieved in any such cases, should have authority to grant injunctions, according to the course and principles of courts of equity," etc. This law was substantially re-enacted in the 17th section of the Patent Law of July 4, 1836 (5 Stat. at L., 117), and the 55th section of that of July 8, 1870 (16 Stat. at L., 198), special pow ers to assess damages in equity cases being also conferred by the latter Act. Before the Act of 1819 was passed, the cirNOTE.-Patents; distinction between inventions and processes; when latter patentable. See note to Corn-cuit courts had cognizance of actions at law brought to recover damages for the infringe ing v. Burden, 56 U. S. (15 How.), 252. ment of patents, but not of suits in equity in * * mode of exercising it is prescribed in precisely the same terms as in previous statutes. In the present case, we see no special reason for sending the case to a court of law or to a jury for trial. There are no such issues depending upon the credibility of witnesses, or on the intricacy of machinery, as to make the case susceptible of easier solution or greater certainty as to the truth, before such a tribunal, than it admits of when presented to the consideration of a chancellor. It would, perhaps, be desirable, if all cases of this sort could be referred to a commission of intelligent experts and practical men to report their opinion thereon, with their reasons, for the final action of the court. A proceeding of this kind was probably in the mind of Congress in passing the Act of Feb. 16, 1875, 18 Stat. at L., 315, authorizing a reference to a jury of five persons. Neither courts nor ordinary juries are perfectly adapted to the investigation of mechanical and scientific questions. The court below, however, exercised its discretion to decide the case upon its merits, without the aid of a jury of any sort, and their action is not a ground of appeal. If we were convinced, however, that the case was not properly decided, and could not be properly decided without such a reference, we might undoubtedly, in the exercise of our own discretion, remand it to the court below for that purpose. But we see nothing in the questions raised which requires that such a course should be adopted. The principal patent sued on in this case was granted on the 21st of April, 1874, being a re-issue of a patent granted to William F. Cochrane on the 6th of January, 1863. The original patent was numbered 37317, and the re-issue 5841. The alleged invention is for a process in manufacturing flour. The patentee, in his speci to increase the production of the best quality of flour; and my improvement consisted in separating from the meal, first the superfine flour and then the pulverulent impurities mingled with the flour producing portions of the middlings meal, so as to make 'white' or 'purified' middlings, which, when reground and rebolted, would yield pure white flour, which, when added to the superfine, would improve the quality of the flour resulting from their union, instead of deteriorating its quality, as had heretofore been the case when the middlings flour was mingled with the superfine." The process employed for producing the result here indicated is then described. It consists in passing the ground meal through a series of bolting-reels clothed with cloth of progressively finer meshes, which pass the superfine flour and retard the escape of the finer and lighter impurities; and, at the same time, subjecting the meal to blasts or currents of air introduced by hollow perforated shafts furnished with pipes so disposed that the force of the blast may act close to the surface of the bolting-cloth; the bolting-chest having an opening at the top for the escape of the air, and of the finer and lighter particles therewith, through a chamber where the particles are arrested, whilst the floor and sides of each compartment of the chest are made close, so as to prevent the escape of the air in any other direction than through the said opening. By this means, the superfine flour is separated, and the fine and The position of Mr. Justice Grier is undoubt-fication, says: "The object of my invention was edly true, that whether a case shall be first tried at law is a matter of discretion, and not of jurisdiction; and in this matter the courts of the United States, sitting as courts of equity in patent cases, are much less disposed than the English courts are to send parties to a jury before assuming to decide upon the merits But the counsel for the defendants suggest that the Revised Statutes have not preserved in entirety the previous enactments on this subject, but have omitted the vesting of original cognizance in the circuit courts sitting as courts of equity in patent cases. From a careful consideration, however, of all the sections of the Revised Statutes on the subject, we think that no intention is evinced to make any change in the law. The original enactments are separated into distinct parts, and somewhat condensed; but the substance of them is retained. By section 629, the circuit courts are invested with jurisdiction, among other things: "Ninth, of all suits at law or in equity arising under the patent or copyright laws of the United States." And, by section 4921, it is declared, that "The several courts vested with jurisdiction of cases arising under the patent laws shall have power to grant injunctions according to the course and prin ciples of courts of equity," etc., following precisely the language used in the Act of 1870, 16 Stat. at L., 198, the last previous revision of this branch of the law. The grant of jurisdiction is as broad and general as it could well be, and the light specks and impurities, which ordinarily | instead of forcing them through the boltingadhere to the middlings and degrade the flour cloth in the same direction with the meal, is produced therefrom, are got rid of; and when also a mere matter of form, and does not belong the middlings are now separated from the other to the substance of the process. The substanportions of the meal, they are white and clean, tial operation of the currents of air in both cases and capable of being reground and rebolted, so is to take up the light impurities and bear them as to produce superfine flour equal in quality away on the aggregate current through the open and even superior to the first installment. flue, and thus to separate them from the midThis is the process described; but the patenteedlings. This, too, may be an improvement on claims that it is not limited to any special ar- Cochrane's method; but it is only an improverangement of machinery. He admits the prior ment. use of currents of air in the interior of the reels, The defendants admit that the process has introduced by means of hollow, perforated produced a revolution in the manufacture of shafts, for the purpose of keeping back the flour; but they attribute that revolution to their speck, and increasing the quantity of superfine improvements. It may be as they say, that it flour; but not for purifying the middlings pre- is greatly due to these. But it cannot be seriparatory to regrinding. His improvement, there- ously denied that Cochrane's invention lies at fore, does not consist in using drafts and cur- the bottom of these improvements, is involved rents of air, but in the process as a whole, com in them, and was itself capable of beneficial prising the application of the blast, and the use, and was put to such use. It had all the carrying off of the fine impurities, whereby the elements and circumstances necessary for sus middlings are purified preparatory to regrind-taining the patent, and cannot be appropriated ing after being separated from the other parts. The defendants deny that they use this process. They purify the middlings of the flour, as before stated, by means of machines constructed according to letters patent issued to Edward P. Welch, in April, 1873, for improvements upon machines patented to Jesse B. Wheeler and Ransom S. Reynolds. by the defendants, even though supplemented by and enveloped in very important and mate rial improvements of their own. We do not perceive that the patent of Cogswell and McKiernan, if valid at all as against Cochrane (a point which will be more fully considered hereafter), affects the question in the least. That patent is not at all for the process In this process, reels are not used for purify- which Cochrane claims. If valid, and if, in ing the middlings, but a flat and slightly in- using his process, Cochrane is obliged to use clined vibrating screen or sieve is used for the any device secured to Cogswell and McKiernan, purpose; over which the ground meal is passed, it does not detract in the slightest degree from and whilst passing is subjected to currents of his own patent. One invention may include air blown through a series of pipes situated within it many others, and each and all may be close underneath the screen; which currents valid at the same time. This only consequence pass up through the screen and through an open- follows: that each inventor is precluded from ing at the top of the chest into a chamber, carry- using inventions made and patented prior to ing with them the finer and lighter impurities, his own, except by license from the owners whereby the middlings are rendered clean and thereof. His invention and his patent are equalwhite, and capable of being reground into su-ly entitled to protection from infringement, as perfine flour. The bolting-chest is made tight if they were independent of any connection with and close on all sides except the opening at the them. top, so that the currents of air may be forced to escape by that exit. Now, except in the use of a flat sieve or screen in place of reels, it is difficult to see any substantial difference between these two methods. The defendants use, in addition, brushes, which revolve on the under side of the screen, so as to keep the meshes thereof constantly clean and free; but this is merely an addition, which does not affect the identity of the two processes in other particulars. We have substantially the same method of cleaning the middlings prepar atory to regrinding by means of currents of air passed through them whilst being bolted, and whilst being confined in a close chest or chamber, said chamber having an opening above for the escape of said currents of air and the impurities with which they become loaded. The middlings being thus purified are reground and rebolted, producing a superfine flour of superior grade; a new, useful and highly valuable result. The use of a flat screen instead of a revolving reel for bolting and cleaning the middlings is a mere matter of form. It may be an improved form and, perhaps, patentable as an improvement; but it is at most an improvement. The forcing of the air-currents upward through the screen and film of meal carried on it and against the downward fall of the meal, That a process may be patentable, irrespective of the particular form of the instrumentalities used, cannot be disputed. If one of the steps of a process be that a certain substance is to be reduced to a powder, it may not be at all material what instrument or machinery is used to effect that object, whether a hammer, a pestle and mortar or a mill. Either may be pointed out; but if the patent is not confined to that particular tool or machine, the use of the others would be an infringement, the general process being the same. A process is a mode of treatment of certain materials to produce a given result. It is an act, or a series of acts, performed upon the subject-matter to be transformed and reduced to a different state or thing. If new and useful, it is just as patentable as is a piece of machinery. In the language of the patent law, it is an art. The machinery pointed out as suitable to perform the process may or may not be new or patentable; whilst the process itself may be altogether new, and produce an entirely new result. The process requires that certain things should be done with certain substances, and in a certain order; but the tools to be used in doing this may be of secondary consequence. The machine patents come next to be consid ered. As to No. 6030, which is a re-issue of the |