delivered the opinion of the Court:

The contention of the appellants on this.appeal is, that the letters, written on behalf of the defendant company, and which have been set forth in full as containing the gravamen of this case, cannot be properly regarded in any legal sense as casting a cloud upon the complainant’s title to his letters patent No. 665,835; that to constitute a cloud upon title some color of title must be shown in the defendant; and that a bill praying for a discovery which would create a cloud upon title and at the same time seeking a removal of such cloud, is demurrable.

*252As stated by this court in the case of Welden v. Stickney, 1 App. D. C. 343, following the repeated decisions of the Supreme Court of the United States in the same regard, it is the rule, in cases of alleged cloud upon title, that equity will interpose only where the pretended title, which is claimed to constitute the cloud, is valid upon its face, and the party in possession will be compelled to resort to extrinsic evidence to show its invalidity, in order to defend his own title. The rule is generally stated with reference to real estate, in connection with which the matter of cloud on title most frequently occurs; but, of course, there is no reason why it should not be applied, as far as it may, to the title to letters patent of the United States for inventions, whereof the title and mode of transfer are to a great extent assimilated to the title and mode of conveyance of real estate. It may be admitted that color of title, so far as that expression is applicable, that is, title apparently valid, but in reality withput foundation in right or justice, must be shown in the defendant company in the present case, in order that the complainant may be entitled to maintain his suit; but we think that very condition of things exists here.

The demurrer of the defendants admits the truth of all the allegations of fact contained in the bill of complaint, with all the reasonable inferences, to be drawn therefrom. Now, it is very plain that the two letters of the defendant company, which have been set forth in the bill, adroitly as they may have been worded in order to avoid the statement of a formal and definite claim, can have no other reasonable meaning than that the defendant company claimed some right of ownership or control over the complainant’s patent No. 665,835, and any and all other patents of the same kind which he should procure. The plain inference from the letters was that no other person could acquire full and valid title thereto, and that the complainant was not at liberty to dispose of his said patent as he sought and desired to do, or to form a corporation to operate the same.

That the effect of this was to cast a cloud upon the complainant’s title, seems to us to be very evident. Equity deals *253with substance, not with shadow. Intentional vagueness of expression, which has all the effect of positive and categorical assertion, must be held in equity to the same consequences as specific allegation. It is not always necessary to state the extent and character of a pretended claim of title in order that it should constitute a cloud upon the true owner’s title which equity will remove. If one asserts the ownership in himself of land which in truth belongs to another, it matters not greatly to this latter, or to those who would deal with him in regard to the land, whether the pretended claim is of a fee simple interest, or of a life estate, or even of a leasehold interest, if the effect is to prevent the true owner from disposing of his land as he is justly entitled to do. The existence of the cloud is one thing; the extent of it is another and a very different thing. It is the province of equity to remove it, if it exists, whether it be great or small, or whatever it may be.

The assertion of the pretended claim of title may be purposely vague and indefinite, as in the present case; and discovery may be proper in order to ascertain its true character and extent, so as that the complainant may be able to meet it "with testimony. But the simple assertion of ownership, without any specification whatever of the character and extent of the ownership, or of the method by which the pretended ownership may have been acquired, would be sufficient to cast a cloud upon title. If the defendant company in this case, instead of veiling its claim in apparent mystery, had simply stated that, by its arrangement with the complainant, it was entitled to the ownership of his patent No. 665,835, there would be but little question as to its assertion, and but little question that such assertion, if unfounded in fact, cast a cloud upon the complainant’s title. This is what it substantially did, although with intentional obscurity.

The argument on behalf of the appellants implies that, inasmuch as the records of the Patent Office show no assignment of the patent by the complainant, and that his title there is entirely clear, therefore there is no cloud upon it, and nothing to prevent the complainant’s free disposal of it. *254But this argument assumes without warrant of law that a cloud upon title can be created only by matter of record. It wholly ignores the case of unrecorded transfers, conveyances, Hens, or other evidences of right, of which parties have notice. Here there were claims, doubtful and indefinite it is true, but positively alleged, of which the letters in question gave notice. It may have been, as intimated by the writer of the letters, that they depended upon representations made by the complainant at the time of the organization of the defendant company. Whatever they were, it was promised that they would probably become the subject of Htigation; and if they were serious enough to become the subject of litigation, the complainant was justified in anticipating such proposed action, and regarding them as a cloud upon his title, which entitled him to the intervention of a court of equity for its removal.

It is very evident that neither party to this cause has fully developed all the facts in the case. The bill of complaint, however, shows sufficient to require an answer from the defendants. If the defendant company has a just claim against the complainant in respect of the latter’s patent No. 665,835, there is no good reason why it should not state it; if its claim, on the other hand, is wholly unfounded and merely a pretense, it is no more than simple justice to the complainant that he should have the opportunity so to show. It is not apparent that the determination of the question will injuriously affect the just rights of the defendant company, or of any party to the cause.

We think that the court below was entirely right in its ruling, and that the preliminary injunction was properly issued. The order appealed from will therefore be affirmed, with costs. And it is so ordered.