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9. Sipaturea of the inventor or inventors, dated as of the time of signing and read and signed and dated by two competent witnesses.
The infarmsbtion for an application for patent, as described, should f u r ~ i s hthe patent attorney all the data needed for the preparation of a preliminary draft of the specification and claims, and when necessary, of the drawings. These should be sent to the inventor or inventors for critical review and comment. The preparation of the draft often will raise questions in the attorney’s mind which had never occurred to him during the conferences with the laboratory personnel. These questions are included in the letter covering the transmittal of the draft. After the inventors have had an opportunity to review the draft, the patent attorney usually has a conference with them to ascertain whether the invention is described accurately and completely.
CHEMICAL PATENT SEARCHES B. E. Lanham U.S. Patent Ofice, Wushington 25, D. C.
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Analyses of inquiries received by the Patent Office stress the fact that most difficulties and failures encountered in patent searching stem from inadequate preanalysis of the problem and inadequate use of the classification facilities. Such difficulties and failures have not been limited by any means t o the novice; experienced searchers, including patent attorneys, have likewise gone astray in the maze of the Patent Office classification which admittedly has shortcomings but which is not nearly so impregnable a fortress as,some imagine it to be. Extensive study and experience are the only adequate instructors in the scientific art of patent searching. Those whose activities have been confined to the field of searching have shown but mild interest in the numerous published articles describing the problems and procedure involved in making a classification. The procedures of searching and classifying are inseparable, however, and a knowledge of one requires some background in the other. It is axiomatic that before an adequate search can be made, a proper analysis both of the subject matter to be searched and the classification system is necessary, followed by a proper correlation of the two. PATENT OFFICE CLASSIFICATION
The Patent Office classification system must provide for documents relating to all branches of the whole of science and technology. Thus, to enable searchers to proceed with a minimum time expenditure to a segment of the arts in which the documents of interest may be found, such arts have been divided into (1)a total of 305 classes of subjects which are in turn further subdivided into (2) subclasses which total over 45,000. The subclasses in each class include a plurality of main, coordmate subclasses which may have subordinate subclasses thereunder in varying degrees of indentation. Each class and subclass is designated by a number and a descriptive title. Of the 305 classes all but 12 have been revised according to modern classification theory; most of the chemical classes are either quite modern in structure or reasonably so. All classes, with their subclasses, are listed in the U. S. Patent Office Manual of Classification, which is considered the key t o the classification system. The manual has an alphabetical index of subject headings which refer to corresponding specific classes and subclassesin the manual. Since the class and subclass titles in the manual are necessarily brief, definitions are provided which set forth the scope of each class and subclass and show what is included therein and excluded therefrom; search notes direct the searcher to related subject matter in other classes and subclasses.
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The manual with its alphabetical index may be obtained from the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C., for $6.00. Classification bulletins containing the subclass schedules with the corresponding class and subclass definitions of many of the classes are obtainable from the Patent Office. Many similarities exist between the Patent Office classification and other scientific classifications but, in addition to the common characteristics, that of the Patent Office has superimposed upon it certain considerations necessitated by the patent laws of the United States. Hence specialized problems in classification are presented. Patent searches require that patents be classified on the basis of inventive or claimed subject matter rather than on general disclosure. Unclaimed but apparently novel features in the disclosures are made available to searchers by means of cross references. The criteria of patentability as dictated by legal considerations constitute the basis of classification adopted for Patent Office use. Such basis is the fundamental characteristic or necessary function or effect of the claimed subject matter rather than a remote or accidental use or application in industries or trades. The basis of classification of chemical compounds is thus their chemical constitution and all compounds of like characteristics are classified together regardless of disclosed uses such as medicine, dye, or insecticide. Compositions of matter (a mixture of two or more ingredients) are classified primarily on the basis of their necessary functions or inherent properties rather than on the basis of ingredients, otherwise compositions that are diverse in nature would be brought together, and such classification, as found by experience, would not suit the primary requirements of a patent search. This primary group including all compositions having like functions and properties-for example, catalysts-is then subdivided, for convenience in searching, on the secondary basis of selected ingredients. Processes of making compounds or compositions are classified with the product produced. Other manufacturing processes may or may not be classified with their products depending on the dictates of experience and the requirements of patent searches. I n class 117, “CoatingProcesses and Miscellaneous Products,” the product8 are included with the processes of making them only if not specifically provided for elsewhere. Machines and chemical apparatus are generally classified on the necessary mode of operation and effect produced rather than on the specific material handled as class 259, “Agitating,” and class 202, “Distillation.” However, other machine classes are based on the material processed-class 80, “Metal Rolling ” Nonmanufacturing processes and the apparatus for performing such processes are usually classified together where a search for one requires a search for the other, as class 209, “Classifying, Separating, and Assorting Solids.” A complete treatment of the subjert of the basis and principles of classification is set forth in referenses (?‘,9). Within a given revised class the subclasses are arranged in descending order of complexity of the inventions-for example, class 241, “Solid Material Comminution or Disintegration,” in which are first placed combinations of the class basic subject matter with features not required for the comminuting action, followed by the basic subject matter, and in turn by subcombinations or elements of the basic subject matter not provided for in other classes. Thus, any given subclass is superior to all coordinate subclasses which succeed it in the schedule, the numerical designations of the subclasses having no significance other than convenient identification. This order of superiority applies to all classes regardless of arrangement, types of subject matter, or whether revised or unrevised. This uniformity in placing patents in a class gives assurance t o a searcher that a search of the first appearing subclass (and possibly those subclasses indented thereunder) which provides for the sought subject matter will constitute the end point of a search, in
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that the sought subject matter should not be found in any 00ordiite subclaw below that deaignated for it. As a further example of thie principle, in class 260, iiChemistry-Carbon Compounds,” subclass 144 and those indented thereunder provide for azo compounds, whereas subclass 239 (coordinate with but below subclass 144in the schedule) and those indented thereunder relate to heterocyclic carbon compounds. Should a search be for a compound having both azo and heterocyclic characteristics, but no characteristic found higher in the schedule than azo, the desired subject matter should be found in subclass 144, which appears first in the schedule; there then is no necessity t o search in the inferior or lower subcIass,239. Lesser parts of such an organization are crose-referenced if novel. Thie rule of superiority applies as well where a patent containa subject matter classifiable in more than one class; the patent is placed in the most complex class capable of receiving it and is cross-referenced,as required, t o the more elemental classes. This may be illustrated by a composition of matter comprising a major amount of a broadly stated mineral lubricating oil and as an additive a minor amount of a specificallydefined carbon compound which per se would be classifiable in class 260, “Carbon Compounds.” The search for such composition would be in class %52, “Compositions,” under subclass 9, “Lubricants,” or those indented thereunder, rather than in class 260, since the composition or combination is more complex or comprehensive than the compound ingredient. More briefly stated, a combination of elements takes precedence over any of its component parts. The superiority, aa between classes which do not involve the question of relative complexity, is resolved by the definitions of the involved classes and the stated superiorities as well as by the prior placement of the patents. The classifier, by means of his definitions, notes, and class plan and structure, haa marked a trail, and the searcher, if the classifier’s directions are followed, will duplicate the latter’s mental processes and arrive a t the specific subclass goal that was intended. PRELIMINARIES AND PROCEDURES FOR SEARCHING
In patent searching, as in other scientificactivities, practice and theory must be complementary. Without adequate groundwork and a proper conception of the probleml the entire search project can be ill-fated from the start. All aspects of the subject matter sought, regardless of type, should be listed in orderly fashion. In the case of a chemical compound and the process of synthesizing it, the precise compound should first be recorded in the form of its molecular structure and by its most obvious name and all ascertainable synonyms thereof. The searcher should know whether the searoh is to be limited to the precise compound, to equivalents thereof, or to generic or specific variations thereof. Such considerations of scope are determined by the purpose of the search. If the intent is to file application for patent, it must be remembered that exaniiners often apply references which they consider the equivalent of or closely related to the claimed invention. Thus consideration should be given to related subject matter such as generally similar compounds, which, however, contain some basic difference-for example, furan and separately classifiable thiophene; both of these are five-memberedring structures, but one contains a heterocyclic oxygen in the ring and the other contains instead a sulfur atom. It is known that these two compounds are analogous and related in the sense that they are susceptible of numerous s i d a r reactions. Thus a search for one may indicate a need for search of the patents to the other. As further examples, a given acid and an ester thereof may be mentioned or a chlorinated compound and the same aompound brominated rather than chlorinated. In considering the processes for making a compound, any other compounds that may be made by equivalents of the sought proc-
eaa, such as by substitution of analogous or related starting
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terials or differences in reaction conditions should be known. A more extended field of search may thus be suggested. All pertinent variables should be referred to from time to time both while outlining the scope of a search and during the search. The human mind is likely to wander from the basic train of thought because of the distractions of patent disclosures not necessarily pertinent to the search. When the scope and approach of a search have been established, the alphabetical index to the Manual of Classification should be consulted. I n many instances the search problem can be solved quickly and adequately in this manner. Should this expedient fail, the titles of the 305 main classes should be scanned in order to select one or more that appear pertinent. The titles are selfexplanatory as to the included general subject matter, and the main class definitions and notes may be referred to for verification. The titles of the major subgroupings of the class (those placed in the first line of indentation) should be studied, reading down the schedule from the top until a title is encountered that is inclusive of the desired subject matter. It should not be necessary, because of the rule of superiority, to consider coordinate major subgroupings lower in the scheduIe. If there are minor subgroups indented to the right under the selected major subgroup, the titles of these should likewise be studied until a subclass is reached that appears to provide for the desired subject matter. Verification should then be made by reference to the pertinent definitions and search notes. Reference t o a n actual case will illustrate the need for adequate search preparation:
A searcher wished to find patents for processes of preparing hydrox lamine, As a result of his experience in patent searchinq he reca$ed that in class 260, “Chemistry-Carbon Compounds ’ there exists a major subgroup of subclasses bearing the titie “Amines” and also one bearinq the title “Hydroxy.” In accordance with the order of superiority within a.class, the first-appearing of the two, subclass 563, “Amines,” and the indentations thereunder were searched, but without result. Then subclass 617, “Hydroxy,” and the indentations thereunder, were Searched, also without result, Patents were found for derivatives of hydroxylamine and corresponding processes; however, these were substituted in a manner beyond the scope of his search and interest. The searcher should have followed the more methodical and remunerative procedure: First, the structural formula of hydroxylamine, “SOB, should have been determined, if not already known, and studied. A glance a t the formula would have shown clearly that the com ound contained no carbon, and class 260 would have been e l h n a t e d from consideration by a mere reading of its title. A study of the main class titles indicates that (other than by ap lication of electrical or wave energy which was not of interest) onfy one other class provides for chemical compounds and roceases of making them (Class 23, “Chemistry”) and it is so deifned. The searcher took the name of the compound a t its face value and thus was misled because the terms amine and hydroxy are usually associated with carbon compounds. In the schedule of class 23, the proper one for the search, there is a subclass, 14, “Compounds,” which is clearly inclusive of hydroxylamine. A further scannin of the titles indented thereunder readily eliminates salts, a&%, and others, since the structural formula of hydroxylamine indicates that it actually is a derivative of ammonia, one hydrogen by an . - atom being -replaced . hydroxy group. Ultimately the searcher will reach subclass 183, “Bases,” which is pertinent, and indented thereunder is subclass 190, “Ammonits Derivatives.” The definition of subclass 190 is: “Bases under subclass 183, which are ammonia, having one or more hydrogens substituted by another radical or element or are ammonia complexes.” Subclass 190 of class 23 then constitutes the proper field of search. This unsuccessful searcher would have spent less time on a brief, worth-while preanal sis of the problem and on the proper search than was consumeJin his precipitous, fruitless search. Reference to the alphabetical index in this instance would have failed to disclose the proper classification for processes of pre-
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paring hydroxylamine. Yet it does include “Hydroxylamine, Organic,” in class 260, subclass 563, which was searched. However, the searcher did not desire to find patents on organic-substituted hydroxylamine processes since he ignored them. There is no search note to class 23, subclass 190, included with the definition of subclass 563 of class 260. It is recognized that there are instances where reference to the alphabetical index and use of the methodical procedure for outlining a field of search do not produce the desired results. Often but one or two patents of interest exist and may not merit mention in the index, subclass titles, or definitions. Under such circumstances, location of the sought subject matter may often be accomplished by searching where analogous subject matter having like fundamental characteristics may be found. For instance, the process limited to placing molten sealing compound between the sides and tops of storage battery cells has no well-defined place in the classification, but by analogy the search for this subject matter would be in class 18, “Plastics,” subclass 59, as a molding and uniting operation, rather than with the art in class 136, “Batteries,” subclass 175, “Assembling Processes.” If it becomes impossible to attain a proper field of search, assistance may be obtained by stating the search problem specifically in writing to the Commissioner of Patents, Washington 25, D. C. A field of search will be prepared for you, but the value of this service depends largely on the adequacy of the request. With the classes and subclasses designated, there will ordinarily
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be included the number of original and cross-reference patents and the number of sheets on which the patent numbers are listed, 100 to a sheet. These lists are available a t a cost of 20 cents per 100 numbers or fraction thereof, and the patents listed may be inspected a t libraries which have patents bound in numerical order. The search may also be made in the public search room in the Commerce Building in Washington, where all U. S. patents are in classified as well as in numerical arrangement. LITERATURE CITED
(1) Bjorksten, Johan, Chem. Eng. News, 26, 1216 (1948). (2) Deller, A. W., “Patent Law for Chemical and Metallurgical Industries,” New York, Chemical Catalog Co., Inc., 1931. (3) Dickerson, Donald L., “Socony-Vacuum Patent Manual,” New York, Socony-Vacuum Oil Co., Inc., 1944. (4) Hoar, R. S., “Patent Tactics and Law,” 3rd ed., New York, The Ronald Press Co., 1950. (5) Litton, James B., presented before the Division of Chemical Literature, 117th Meeting, AMERICAN CHEMICAL SOCIETY, Houston, Tex. (6) Palmer, A. M., “University Patent Policies, Practices, and Procedures,” American Council on Education, January 1948. (7) Rosa, Manuel C., J . Patent Ofice Soc., 29, 241 (1947). (8) Thomas, Edward, “Chemical Inventions and Chemical Patents,” New York, Clark Boardman Co., Ltd., 1950. (9) U. S. Patent Office, “Classification of Patents,” 2nd rev., Washington 26, D. C., U. S. Govt. Printing Office, 1946. RECEIVED July 20, 1951.
The second p a r t of the symposium, “Evolution of a Patent,’’ was published in Chemical and Engineering News a s follows: October 22: “Dynamics of Patent Practice,” W. L. Cheesman, U. S. D e p a r t m e n t of Agriculture. “Chemical Patent Practice,” Pike H. Sullivan, S t a n d a r d Oil Co. (Indiana). October 29 : “Handling Chemical Patent Applications,” Earl P. Stevenson a n d F r a n k N. Houghton, A r t h u r D. Little, Inc. “The Corporate P a t e n t Department,’’ A r t h u r B. Bakalar, Shell Development Co.
Butadiene Polymers for Low Temperature Service J
ROSS E. MORRIS, JOSEPH W. HOLLISTER, AND FRANK L. SHEW Rubber Laboratory, Mare Island Naval Shipyard, Vallejo, Calif.
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N T H E course of preparing naval vessel8 to maneuver in the Arctic, the problem has arisen of providing rubber gaskets which recover rapidly from compression a t temperatures as low as -35’ F. The task of developing a suitable gasket stock was assigned to this laboratory by the Bureau of Ships. Previous work (9,10) has shown that regular GR-S is generally satisfactory for this application because its vuIcanizates do not crystallize or undergo second-order transition a t -35” F. Furthermore, this rubber is low in cost and is readily available. During the past several years the Office of Rubber Reserve and, to a lesser extent, the Phillips Petroleum Co. have made experimental polybutadienes and butadiene-styrene copolymers for evaluation by Defense Department laboratories. These rubbers have differed in polymerization temperature and, in the case of the copolymers, in styrene content. Since regular GR-S, the prototype of these rubbers, has been found to be suitable for use in the manufacture of gaskets for service a t temperatures as low as -35” F., it is desirable to ascertain whether any of the experimental rubbers are better than GR-S for this purpose. Some information on the low temperature properties of polybutadienes and butadiene-styrene copolymers has been pub-
lished. Beu et al. ( 1 ) found by x-ray studies on unvuloanized rubbers that polybutadienes polymerized a t 86” F. and a t lower temperatures crystallized to some extent when stretched 300% a t 32’ F. and cooled to -22” F. Polybutadiene polymerized a t 104”F. did not crystallize. A 90/10 (charge ratio) butadienestyrene copolymer prepared a t 4’ F. and containing 6.8% bound styrene crystallized under these conditions, but an 80/20 co~~
~
The purpose of this investigation was t o d e t e r m i n e whether o r not butadiene-styrene copolymers with a different ratio of these constituents and/or a different polymerization t e m p e r a t u r e t h a n standard GR-S a r e better rubbers for the m a n u f a c t u r e of gaskets for low t e m p e r a t u r e service than s t a n d a r d GR-S. The butadiene-styrene copolymers tested totaled 34. T h e cold compression set test performed a t -35” F.wasused t o evaluate the suitability of these rubbers for gasket service. Six copolymers yielded vulcanizates having stable compressioh sets considerably lower t h a n the compression
