In this respect the decision of the board in the instant case differs from its decision in the case of In re Crowell, supra, which was affirmed by us.

There certain method claims were involved. They were rejected by the examiner upon both prior art and estoppel, he being of the opinion that there would be no invention in substituting certain elements of certain references cited for a particular element shown in another patent to Crowell. The board stated its disagreement with the examiner upon this point, but expressly held that the limitations inserted in the claims there appealed, which did not appear in the claims that there had been cancelled, were "old steps," and hence patentability was not involved by adding them to the cancelled claims.

There was nothing in the board's opinion in that case to indicate that if the applicant had not cancelled the claims, but had amended them by inserting the limitations, they would, in its view, have been allowable over the prior art. Here, as has been indicated, it seems clear that had applicant, instead of cancelling, amended the claims by inserting the limitations, they (except claim No. 13) would, in the opinion of the board, have been allowable.

Under this state of facts, it does not seem to us that the doctrine of estoppel may properly be applied.

The board quotes cancelled claim No. 6 "as representative of the cancelled claims most closely related to the claims on appeal." It reads:

6. Well casing having a ported section, valvular means for the port, a plug adapted to close the entire bore of the casing and adapted to be lowered in the casing for opening the valvular means, and a second plug adapted to be lowered in the casing in back of the first plug.

The board then said:

It will be noted that this claim specifies a plug adapted to close the entire bore of the casing and in our opinion this necessarily means a plug slidably fitting the bore and capable of being forced down by fluid pressure. We consider, therefore, that this claim is as restricted as the appealed claims.

It is difficult to reconcile this holding with the prior holding where the claims were measured by the patent to Manning, and found to be patentable over Manning.

It may be said that, on behalf of appellant, it is pointed out. that many of the new claims contain limitations other than the slidably fitting plug limitation. These are not discussed in the board's decision, and we do not find it necessary to discuss them here. Just how important any of the limitations may be in a practical sense, we do not undertake to say. They seemed to the board to be of sufficient importance in a patentable sense to distinguish from the Manning patent, and we think that by the same reasoning

they may properly be held so to distinguish from the cancelled claims as to justify their allowance.

The foregoing, however, does not apply to claim No. 13. We think it was properly rejected upon the prior art.

For the purpose of clarity, it seems proper to draw attention to the fact that one distinction, not hereinbefore noted, between this case and the case of In re Crowell, supra, is that here the cancelled claims were cancelled from appellant's divisional application, serial No. 208,539, while in the earlier case the cancelled claim upon which the issue turned was cancelled from appellant's so-called parent application, serial No. 171,851 (and not from the divisional application, serial No. 331,411, which matured into the patent, reissue of which was there sought), and to the further fact that, in the instant case, the record upon which we have to determine the controversy contains nothing which admits of our considering the claim there cancelled, quoted in our opinion there, in measuring the claims here appealed, and we have not done so.

The decision of the Board of Appeals is affirmed as to claim No. 13, and reversed as to claims numbered 1 to 10, inclusive, and 17 to 19, inclusive.

465 O. G. 462; 23 C. C. P. A. 864; 81 F. (2d) 548

IN RE GARREAU (No. 3582)

PATENTS-PATENTABILITY-ANTICIPATION.

Claims to a method of burning powdered fuel held not patentable in view of the prior art of record.

United States Court of Customs and Patent Appeals, February 3,

1936

APPEAL from Patent Office, Serial No. 376646

[Affirmed.]

Langner, Parry, Card & Langner (E. F. Wenderoth and John E. Lind of counsel) for appellant.

R. F. Whitehead (Howard S. Miller of counsel) for the Commissioner of Patents.

[Oral argument January 10, 1936, by Mr. Lind and Mr. Miller] Before GRAHAM, Presiding Judge, and BLAND, HATFIELD, GARRETT, and LENROOT, Associate Judges

LENROOT, Judge, delivered the opinion of the court:

This is an appeal from a decision of the Board of Appeals of the United States Patent Office, affirming a decision of the examiner, rejecting all of the claims of appellant's application for want of patentability in view of the prior art.

The rejected claims are three in number and read as follows:

24. The method of burning powdered fuel which comprises mixing said powdered fuel with air, then forcing said air and fuel through a plurality of narrow passages through non-combustible and heat conductible material while gradually subjecting said fuel and air to increased heat to reach the ignition and combustion points.

25. The method of burning powdered fuel which comprises mixing said powdered fuel with heated air, then forcing said air and fuel through narrow passages provided in a non-combustible and heat conductible material while gradually increasing the temperature of said fuel and air to the igniting point.

26. The method of burning powdered fuel which comprises mixing said powdered fuel with heated air, then forcing said air and fuel through a pile of non-combustible and heat conductible blocks while the outlet surface of said blocks is maintained in incandescent state.

The references cited are:

Bourne (Br.), 3,594, of 1868.

Wolvin, 1,063,489, June 3, 1913.

Batchelor, 1,296,906, March 11, 1919.

The alleged invention is described by the Board of Appeals in its decision as follows:

The invention relates to a method of burning powdered fuel. In Figs. 1 to 10 applicant has illustrated an apparatus by which the method may be carried out. A mass of heat conducting blocks is placed in a chamber adjacent to a furnace or boiler. This mass may be heated to incandescence in any manner. The heat from the furnace will evidently keep it heated after the burning has begun. A mixture of powdered fuel and air is forced through the mass of blocks. The air and fuel are thoroughly commingled by the blocks and burn therein. The temperature of the blocks is lowest when the fuel enters so that as the mixture passes through the mass the temperature of it is gradually raised and is highest at the point where the mixture leaves the mass. At that point it is fully ignited and burns.

The patent to Batchelor discloses a furnace having a grate which divides the furnace into an upper and lower combustion chamber. A mass of porous material is placed upon the grate. A mixture of air and fuel is introduced into the lower chamber, is ignited by a pilot burner therein and burns. The partly consumed products of combustion pass up through the grate and the hot porous mass and are completely burned in the upper chamber.

In the patent to Wolvin there is disclosed a boiler furnace having a chamber at the front end and a series of baffles of checker brick work arranged at the rear end. A mixture of fine fuel and steam is forced into the chamber, where it burns to some extent, and then passes through the checker brick work where further combustion - takes place.

The patent to Bourne discloses several forms of apparatus. That shown in Figures 3 and 4 was specially referred to by the board and

discloses a steam boiler furnace with a combustion chamber separated into upper and lower parts by bars or a perforated arch which, the patent states, are composed of firebrick. The floor of the lower part of the chamber is filled with material which the patent states consists of pieces of firebrick or other intractable material. Between the said bars and the top of the firebrick in the bottom of the chamber there is a very considerable empty space in which no flames are indicated in the drawing, but flames are indicated in that part of the chamber over the said bars separating the chamber. With respect to the operation of the apparatus shown in said Figure 3 the patent states:

In this boiler the air is heated by being brought down through a casing encircling the chimney and the boiler, and it is projected with the fuel through twyeres into a combustion chamber placed beneath the bars, which are of firebrick, and the coal dust ascending through them is burnt as before. This species of draught is one of those which I term an equivalent of the descending draught, as although the draught in reality ascends through the fire the action is the same as if it descended, since the coal dust mingled with air equally passes through the fire as in a descending draught it would necessarily do. A side draught in which the coal dust is carried sideways through or among hot bodies may it is obvious be easily arranged upon the same principle, and such a draught would also be equivalent to a descending draught. The coal dust is fed in by feeding rollers rotating slowly in hoppers as before, or by any other equivalent arrangement, and falling through slanted pipes before jets of steam, which should be superheated, it is carried with the air into the combustion chamber beneath the firebrick bars or perforated arch and finally ascends through the fire. In the combustion chamber pieces of firebrick or other intractable material may be laid, or pigeon hole passages may be built, but so formed as to let out the slag, which will flow out by a hole as before.

The Bourne patent discloses other forms of the invention whereby the fuel is fed directly on the top of the firebrick bars in the upper part of the chamber, and from there the products of combustion pass downward to the lower part of the chamber, and then upward through fireclay pipes into the boiler to generate steam.

With respect to the invention generally the patent states:

What I claim as new in this part of my Invention is the combination in common furnaces of the use of coal dust fuel with a descending draught, or its equivalent, in the form of a side or other draught so arranged that the dust is constrained to pass through the fire whether such fire, or incandescent mass answering the purpose of a fire, be formed of coal, or brick, or pumice stone, or other intractable material with or without coal, or of a mixture of all or any of these substances, and also of the use in furnaces of firebrick tiles disposed in an arch or otherwise, or of perforated fire-blocks or arches when combined with the use of coal dust, so that the flame and products of combustion, and also the slag, may descend through such openings or perforations made in a bed of intractable material capable of withstanding a very high degree of heat, whereby the dust which would otherwise pass into the flues and up the chimney is wholly consumed. The coal entering as dust on

this system being in a state of minute subdivision and presenting a large surface to the air, with which moreover it is intimately mixed, it will explode to some extent like gunpowder, and the sudden explosion or combustion will generate a pressure at the point where the combustion takes place which will increase the intimacy of the contact and so favor combination. By this action, and also by the diffusion of the combustible particles, less air will be required to enter the furnace than is usually admitted to common furnaces burning the same quantity of fuel, since nearly the whole of the oxygen which is sent in will enter into combination and less fuel will suffice to generate a given quantity of steam since there will be less waste in heating air which merely passes through the fire without any part of it entering into combination, and which waste air amounts in common furnaces to as much, or nearly so, as the quantity really utilized.

With respect to the "incandescent mass" referred to in the patent, it is not very clear whether this was intended to include the intractable material in the bottom of the chamber shown in said Figure 3 or was intended to include only such material which separates the chamber. The drawing would indicate that the latter was intended for, as has been stated, no flames are indicated in the space between such material in the lower part of the chamber and the bars separating the chamber into two parts.

Inasmuch as it is our opinion that the claims here involved are not patentable in view of the reference Bourne, it is not necessary for us to consider the other references.

It is appellant's contention that in the Bourne construction the air and fuel pass through the firebrick in the lower part of the combustion chamber, are there intermingled, and that, to quote from the brief of counsel for appellant,

the firebrick located at the bottom of the combustion chamber merely slows up the passage of the mixture through the combustion space so as not to carry the fuel particles too swiftly through the fire. There is no gradual raising of the temperature of the fuel mixture as specifically called for in applicant's claims until the ignition point is reached. In the Bourne construction after the mixture of fuel and air passes through the firebrick, then as clearly shown in Figure 3, there is a space directly below the tiles of firebrick or perforated arches b where the mixture encounters nothing. In this space the mixture which has been heated by the heated air and the steam necessarily must cool to some extent and then above the perforated arches b the combustion itself takes place in the manner of an explosion.

In applicant's method there is a gradual and continued raising of temperature until the ignition point. In Bourne's method there is no such gradual raising of temperature since the fuel is immediately heated by the superheated steam and is then cooled during its passage through the firebrick and cooled still more in the space directly below where the combustion takes place.

Accepting appellant's theory of the operation of the Bourne apparatus above described, that the firebrick in the lower part of his combustion chamber is not heated to incandescence, but serves to