January, 1927
INDUSTRIAL A N D ENGINEERING CHEMISTRY
bore any relation to crystal structure. Cobalt a t room temperature can exist as a hexagonal and as a face-centered cubic crystal. The working temperature undoubtedly affects the structure to some extent. I n Table I, where cobalt is promoted with 1 per cent of the metal oxide, the crystal structures of the metals are fairly well distributed, no type predominating in any section. Description of the structure of the oxide crystals was not sufficiently complete in available literature for any substantial comparison to be made. There was considered the possibility of the unit edge of the crystal exerting some influence upon the direction of the reaction or upon the relative activity, but the scattering data prevented any definiteness. With the available data, no grouping as to length of the unit edge appeared. Short and long occurred in all sections of the table. A grouping was observed when the melting points of the metals were compared. All the metals which increased activity have melting points lower than cobalt. That of iron, however, lies only slightly above that of cobalt. The metals with high melting points were consist,ent in their activity, giving signs of actually poisoning the cobalt. Cadmium and magnesium were exceptions. I n spite of low melting points they showed marked effect in decreasing the activity of cobalt. Theory of Catalysis
I n the process of the work, constant vigilance was maintained for any clue which might have a bearing upon the theory of catalysis, especially as conditioned in contact catalytic processes. Nearly every catalyst used showed some peculiarity specifk to i t alone. Operation factors, such as velocity of gas, optimum temperature, physical structure of catalysts, were the variables chiefly encountered. It is certain that physical structure is important, especially at the temperature of this reaction. Ruggedness of the catalysts is an absolute necessity. This is demonstrated when cobalt is promoted with either lead or bismuth. Small quantities accelerate the activity and continue to increase the efficiency until the quantity of promoter substances approaches 3 per cent. Above this amount, ihe efficiency slowly decreased, followed by sintering, showing that a small quantity associated in the interfaces of the cobalt crystal assist probably in the diffusion and vaporization of the atom along the active edges and centers of the catalysts.
173
Wyckoff states that, in cobalt-iron alloys, the mixtures are homogeneous in all proportions. The cobalt crystal becomes apparent only when the alloy consists of more than 98 per cent cobalt. From Tables I to I11 it is seen that a catalyst with 1 per cent iron produces no effect over that of cobalt alone. When the catalyst is promoted with 3 per cent iron, its efficiency is increased 9 per cent. As previously noted, this is the range where the cobalt crystal is changing. When the iron content is increased to 9 per cent, the efficiency drops to practically the same as cobalt. Thus, while alteration of the crystal structure is being effected, a maximum change is occurring in the active edges and active points, developing the highest percentage conversion. As the iron increases, the crystals of the catalyst become evenly uniform and consequently less active, as can be observed. The conversion stops a t N2and NzO,suggesting that now the weak chemical affinity of the active edges and points have become fixed by the presence of increased amounts of iron. The cobalt-aluminum catalyst is interesting, first, because it gave the highest efficiency of all the catalysts tested. Secondly, its activity, as is noted in Figure 1, is uniformly proportional to the quantity of aluminum oxide present, until it has reached the peak. It follows a high level, dropping slowly a t first, then very rapidly, to the phase where cobalt becomes the promoter, Among a large number of papers treating absorption, not a few treat of the sorption power of a l u m i n ~ m , ’also ~ with respect to its dehydration reaction and its sorption of water vapor over a range of temperatures varying from 200’ to 800” C.,I6 which is just within the range of this experiment, as measured by the pyrometer (690’ to 800” C.). It is a very common practice to use the blast flame to dehydrate alumina; consequently, when water vapor is added to the gas mixture the decrease of t h e conversion factor may be due to the hydration of a portion of the active edges and centers of the catalysts. K h y is it that water of the reaction is not absorbed similarly a t all times? Possibly the introduction of a common molecule disturbs the equilibrium of desorption, affecting the direction and increasing the probability of the formation of the water, forcing a slight shortage of nascent oxygen in the immediate zone of action, thus permitting the molecules of nitrogen to form. 16 16
.
Sabatier, “Catalysis in Organic Chemistry,” Van Nostrand Co 1922. J . Phus. Chem , 30, 2 (1926).
An Improved Method of Organic Microcombustion’ By George Kemmerer and L. T. Hallett CHEMICAL
LABORATORY, UNIVERSITY
OF WISCONSIN,
MADISON, WIS.
Improvements in Pregl’s microcombustion method are described which make it practicablef o r the accurate determination of carbon and hydrogen where only small samples are available. The use of a sealable microabsorption tube and a special electric furnace accounts for the greater accuracy. S THE scientific study of the lakes of WisconsinlJ,* and the northwestern lakes of the United States6 has progressed, more accurate methods of chemical analysis have become necessary. This is especially true in the analysis of the residues from the soft water lakes of northern Wisconsin,’ where a very large volume of water must be evaporated or a small sample used. The determi-
A
Received August 30, 1926. Birge and Juday, Wisconsin Geological and Natural History Survey, Bull. 22. 3 Juday, T r a n ~ Wisco?isin . A c a d . Sci., 16 ( l ) ,17 (1909). 4 Domogalla, Juday, and Peterson, “Forms of Nitrogen Found in Certain Lake Waters,” J . Bioi. Chem., 63, 269 (1925). 3 Kemmerer, Bovard, and Boorman, Bur. Fisheries, Bull. 39, Document 944 (1923-24;. 1
2
nation of carbon and hydrogen by ordinary combustion methods from the small residue obtained by evaporating 1 to 6 liters of water is not practicable. The PreglG microcombustion method, with gas furnace and apparatus as described by him, gave fairly satisfactory results, but the method seemed capable of improvement. I n the first place, the temperature of the gas furnace could not be accurately controlled and a temperature high enough to decompose the carbonates of calcium and magnesium could not be obtained. T o overcome this an electric furnace was built in sections to take the place of the various heating units of the Pregl furnace.
* “Quantitative Organic Micro Analysis,” translated
by Fyleman, p. 15.
INDUSTRIAL A N D ENGINEEI1ING CHEMISTRY
174
The most important change from the Pregl method was the use of sealable microabsorption tubes, which made i t practicable to weigh these tubes while filled with oxygen, similarly to the method used in the determination of carbon in steel. This greatly reduced the error caused by replacement of the oxygen with air. Description of Furnaces
Three simple tube furnaces were constructed by winding Eo. 30 niclirome wire on 9-, IS, and 7-em. sections of a 1.4-em. (inside diameter) porcelain tube. (Figure 1) The first section (F 1) was wound with 365 em., tlie second ( F 2 ) with 730 em. and the third (F 3) witli 730 em. of the wire. The amount and size of this wire could he varied because 1
I
L
R 2~. ~ . . . ~~~~
I
L----.”’__ ~~
Flgure 1
-
‘,I
each furnace was controlled by a separate rheostat ( E 1, R 2, R 3). After the wire was wound on the tube, an ashestos cord was wound between the wires and the whole covered with alundum cement. The ends of each furnace were made of circles of 4mm. hardened asbestos hoard, 7 em. in diameter. Each furnace was covered with a sheet aluminum shell and the space between filled with magnesium oxide and asbestos. One wire from each furnace was grounded to the shell clamp and the three sections were arranged to slide on two parallel 7-mm. brass rods. (Fignre 2) One of theae rods served as one pole of the 110-volt a. c. heating current. The other pole of each section was connected through a rheostat, and by means of suitable switches (Figure 1) the current used to heat the last two furnaces could he read on a small a. e. ammeter. The temperature of each furnace was carefully determined by means of a thermocouple type pyrometer.
Figure 2
GAS TKAIN-The oxygen was supplied from rylinders, each of which was tested for hydrogen although it had been prepared hy the liquid air process. The gas train of Pregl was simplified by the elimination of
Vol. 19, No. 1
the air train to wash oxygen from the apparatus. The Pregl pressure regulator was used, but it was filled with coneentrated sulfuric acid in place of potassium hydroxide solution. The bubble counter and U-tube used by Pregl were modified and arranged to connect directly to the pressure reylator and combustion tube. (Figure 3) The modified tube, 8.5 em. long by 1.5 em. in diameter, was made of Pyrex glass with a pound-glass joint sealed with glass cement. This eliminated two rubber connections. It \;as more easily filled than the U-tube and the Pyrex glass eliminated the danger of cracking while sealing. The tube was filled u-ith ascarite a n d phosphorus pentoxide. The bubble counter was filled with concentrated sulfuric acid. CoMnUmloK Tuum-Since the water residues contained calcium and magnesium carbonate which had to be decomposed, the Pyrex combustion tube first used was replaced by a silica tube. This tube, 53 em. long and 7 mm. in diameter, was filled as recommended by Pregl,7 except that lead chromate was omitted because t.1ie residues and compounds used did not contain sulfur except in the form of sulfates. I n the longer tube the materials following the boat were: silver wool, 3 em.; finely broken copper oxide, 15 c m ; silver 1%-001,3 em.; lead peroxide, 4.5 cm.; :mid silver wool, 1.5 em. Tile filling recommended by Wise8 gave good results wit,li larger samp!es but the above arrangement has bccn chosen for routine work. In addition to the three sections of tlre electric furnace already described, the constricted end of ilie conibustion tube was heated by a small coil of No. 30 niclirome wire which was wound on an asbestos form and placed just at the end of the cornbustion tube. (Figure 1, €1) This was
=i
Figure 3
never heated hot enough to injure the rubber connection. I t was found much more effective than the hot wire or copper rod used by others. ABSOWTI~N TUBE-Except for the Blumers ahsorption tube we find no reference to the use of a microahsorption tube which can he sealed. The use of glass stopcocks adds materially to the weight of the tube and the lubricant necessary adds an extrn source of error in weighing. To overcome these difficulties a tube was so designed that both capillary ends could be sealed by drops of mercury which, when the tube was rotated 90 degrees, fell back into little pockets and allowed the free passage of the gas while the tube was in use. Extra hulbs were pror7ided near the end of each capillary to prevent loss of mercury. The tube was of Pyrex glass and a single ground joint was sealed with glass cement. so that it was not difficult to make and it weighed very little more than the Pregl tube. (For further details of construction refer to Figure 4.) It should be noted that the curves and capillaries are slightly exaggerated in tlie drawing. The tubes were made of 6-mm. Pyrex ground-glass joints. The total length of the carbon dioxide t.ube was 16.5 em. and the water absorption tube was slightly shorter. The filled tubes veighed between 10 and 12 grams 7
L O i ~Cd., p. 25.
1.Am. Chrm. Soa, $9.2055 (1917). 9
Pregl, ioc. ‘il., P. 42.
January, 1927
INDUSTRIAL AND ENGINEERING CHEMISTRY
a n d therefore were readily weighed on a microbalance with a maximum load of 20 grams. Various drying agents were tested in the water absorption tube. I n each case the same agent was used to dry the gas before i t entered the combustion tube. Calcium chloride gave fairly satisfactory results but the tubes had to be refilled often, and each time that the absorption tube was refilled the drying tube and the head of the train had also to be refilled. Magnesium perchlorate trihydrate gave very satisfactory results but required a slightly longer absorption tube than phosphorus pentoxide.
Figure 4
hfercury
Phosphorus pentoxide had the greatest absorbing power for its weight and it was not necessary to refill the apparatus as often. It should be noted that it would not be as satisfactory if the tubes were not sealable. With these facts in mind phosphorus pentoxide was chosen. It was mixed with a small amount of fine glass wool so that it would not retard t h e flow of gas greatly. Soda lime and ascarite have been used in the carbon dioxide tubes. To get the best results with soda lime its moisture content must be controlled quite accurately and the passing of the dry gases reduces this moisture content. Compared with ascarite i t has a small capacity for absorbing carbon dioxide and it is impossible to tell when it is saturated. With ascarite the degree of saturation can readily be determined by its change in color. For ordinary conibustion work ascarite is said to act as its own drying agent but in micro work it has been found advisable to follow it with a 1-cm. layer of phosphorus pentoxide. Tubes filled in this way gave the most satisfactory results.
f
Overflow
175
to the atmosphere before removing the absorption tubes (1, Figure 5 ) . By turning stopcocks 2 and 3 (Figure 5 ) i t was possible to fill the bottle without removal from the stand. Method of Analysis
The lake water residues in which carbon and hydrogen were determined were dried in an electrically heated desiccator over phosphorus pentoxide for one week at a temperature of 55' C., under a pressure of 10 cm. of mercury. Sugar and other compounds were dried in a desiccator over phosphorus pentoxide. Samples of 6 to 10 mg. of the dried material were weighed into the micro boats and placed in the desiccator for 12 hours. They were then quickly reweighed and replaced in the desiccator for 4 hours before the combustion. This was especially necessary during the summer, when the samples were found to absorb moisture during weighing. Table I i
SAMPLE ~ V E I G K T Mg.
CALCULATED
FOUND
CARBON
HYDROGEN
CARBON
HYDROGZN
Per cent
Per cent
Per cent
Per cent
Table, I1 COMPOUND . Hippuric acid Succinic acid Benzaldehyde
\\'EIGHT OF SAMPLE
Mg.
(1) 4 . 7 3 3 (2) 5 . 3 6 6 9.190 (1) 5 . 3 0 4 (2) 6 . 7 3 6
CALCULATED CARBON
HYDROGEN
FOUND
Per cent
Per cent
CARBON
HYDROGEN
60.32
5.06
40.67 79.22
5.12 5.70
60.32 60.29 40.59 79.28 79.33
5.35 5.08 5.06 5.84 5.87
Per cent
Per cent
The furnaces were first heated to the following temperatures: N o . 1, 900" C., No. 2, 650" C.; No. 3, 180" C. The absorption tubes were attached to the train and a blank run made, allowing 300 cc. of oxygen to pass through in 30 minutes. A study of the rate of flow of the oxygen during combustion revealed the fact that it should be slower during the earlier stages, while the final washing out of the carbon dioxide could be more rapid. Two hundred cubic centimeters of oxygen were used during the first 25 minutes and 100 cc. additional were passed through in the next 5 minutes. For the regular organic compounds only about 20 minutes is required to complete a combustion. Each absorption tube was wiped with a damp 'cloth and carefully dried before it was attached for the day's run. After a run the tubes were removed from the apparatus by touching only the ends, which were then carefully wiped. Table I11 ~
sanpLEw B I G H T OF SAMPLB Mg.
1 2 3
T o absorption tube
4
5 6
Figure 5
The aspirator bottle or the Mariotte flask which was used t o regulate the pressure in the apparatus and to measure the amount of oxygen passing through was so arranged that two definite pressures could be obtained by the use of two 3way stopcocks on outlets 2 and 3, Figure 5 . The 3-way stopcock in the oxygen line made it possible to open this line
(a) 8.114
( b ) 7.517 (a) 8.114 (b) 6.783 ( a ) 7.176 (b) 9.522 ( a ) 11.945 ( b ) 15.462 (a) 8.147 (b) 4.979 ( a ) 5.074 (b) 5.798
CARBON Per cent 11.79 11.77 15.48 15.37 11.34 11.23 8.33 8.21 16.04 16.10 11.91 11.87
HYDROGEN Per cent 1.67 1.61 1.50 1.45 1.50 1.47
They were always removed with the oxygen valve (1, Figure 5) open to the air so that there mas a slight positive pressure within, which prevented any moisture or air from passing through the capillaries into the tubes. On disconnecting a tube it is rotated 180 degrees and shaken slightly to seal the tube. This operation required from 1 to 2 seconds, sufficient
INDUSTRIAL A N D ENGINEERING CHEMISTRY
176
time for the oxygen pressure in the tube to become equal to atmospheric pressure. WEIGHING-After standing on a glass rack near the balance for 15 minutes a tube was allowed to stand on the balance for 5 minutes before the final reading. It was found by trial that a tube did not gain in weight if allowed to stand in the balance two hours longer. The results obtained by the analysis of recrystallized pure sucrose are given in Table I. Results of analysis of certain other compounds are to be found in Table 11. Results typical of those obtained by analyzing over one hundred lake water residues are recorded in Table 111.
Vol. 19, No. 1 T a b l e IV
CARBON SAXPLE WEIGHTOF S A M P ~ E MICRO METHOD M A C R O METHOD Mg. Per cent Per cent 1 2 3
( a ) 7.153 ( b ) 5.752 ( a ) 5.944 (5) 7.045 (a) 5.426 ( b ) 5.925
19.11 18.92 18.56 18.70 20.06 20.16
18.9 18.5 19.7
.Three samples of lake residues were submitted for the independent determination of total carbon by the micro and macro methods. Results are in Table IV. The weight of the sample taken for microcombustion is given in each case.
An Outline of the Law of Chemical Patents’ By Edward Thomas 165 BROADWAY, NEW Y O R K , N. Y.
The N a t u r e and Form of a Patent
U
NITED STATES patents for inventions are authorized by the Constitution, which says, Article I, Section VIII,
“The Congress shall have power to promote the progress of Science and Useful Arts, by securing for limited Times t o Authors and Inventors the exclusive Right to their respective Writings and Discoveries.” Congress has exercised its power by enacting various patent statutes, culminating in the present statute. Pursuant t o this Statute, a United States patent as issued by the Patent Office is a legal document consisting of three principal parts : 1-A contract form drafted, furnished, and filled out and signed by the Commissioner of Patents. 2-A specification drafted by the inventor or his attorney, disclosing his invention and “how the combination will operate,” t o quote Judge Hand. 3-One or more “claims,” also drawn by the inventor or his attorney, subject to the criticism of a n Examiner in the Patent Office, and defining the invention which has been described in the specification.
A United States patent runs for seventeen years from the date of its issue, the d a y the Commissioner signs it. A “copy of a patent” as sold by the Patent Office consists of a copy of the specification and claims bearing a notation of its filing and issue ‘ dates. The Court of Appeals for the Third Circuit explains the nature of the legal document, saying: An American patent is a written contract between a n inventor and the Government * * * The consideration given on the part of the inventor t o the Government is the disclosure of his invention in such plain and full terms t h a t any one skilled in the art t o which i t appertains may practice it. The consideration on the part of the Government given to the patentee for such disclosure is a monopoly for seventeen years of the invention t o the extent of the claims allowed in the patent. Fried. Krupp Actien-Gesellschaft v. Midvale Steel Co., 191 Fed. at 59A2
The inventor gets the privilege t o exclude the public from its common-law rights for a definite term. The public gets the advantage of a disclosure of something new, which the inventor might otherwise have left secret. Waterbury Buckle Co. v. G. E. Prentice Mfg. Co., 294 Fed. at 938. Widely separated courts have agreed that: The object of the patent law is to protect the inventor, not in some paper ideal, but in his actual contribution to the useful arts. Los Angeles Lime Co. v. Nye, 270 Fed. a t 160, quoting Asbestos Shingle, Slate and S. Co. v. Rock Fiber Mfg. Co., 217 Fed. a t 66. Or, as put by Judge Learned Hand: An inventor must do more than give cues for future experiments * * * Unless he is dealing with elements whose action and reaction is known and certain, he is bound to disclose how the combination will operate. A patent is the reward of a tested contribution t o the art, not of a pregnant surmise or a promising hypothesis. H. Ward Leonard, Inc. v. Maxwell Motor Sales Corp., 252 Fed. at 590. The Supreme Court has said: The specification and claims of a patent, particularly if the invention be at all complicated, constitiite one of the most difficult legal instruments to draw with accuracy, and in view of the fact that valuable inventions are often placed in the hands of inexperienced persons to prepare such specifications and claims, i t is no matter of surprise t h a t the latter frequently fail to describe with requisite certainty the exact inventfon of the patentee, and err either in claiming t h a t which the patentee has not in fact invented. or in omitting some element which was a valuable or essential part of his actual invention. Topliff v. Topliff, 145 U. S. at 171.
Another court has summed up the mutual advantages resulting from well-prepared patents:
It is obvious, therefore, t h a t many obscure problems of law rise in dealing with inventions and in preparing and studying patents. The only certain way t o solve such a problem is t o ascertain what the Courts have already decided in similar cases because, as was said by Commissioner of Patents Doolittle, “The United States Courts are the authoritative expositors of the patent law.” Chambers and Mendham v. Duncan, Wilson and Lauder, 10 0. G. 787.
T h e series of three articles, ot which this 1s 1 Received June 28, 1926. t h e first, is based to some extent on t h e author’s forthcoming book “ T h e Law of Chemical Patents.” This book will be a case book, each chapter commencing with t h e discussion of a principle which will be illustrated by extracts from pertinent cases a n d decisions, concluding with a summary of t h e inlormation. T h e book will be issued within a month b y t h e D. Van Nostrand Co., New York. 8 T h e abbreviations are those customarily used by lawyers. Thus 191 Fed. a t 594, signifies t h a t t h e case is reported in volume 191 of the Federal Reporter and the exact location of the quotation is a t page 594. T h e Federal Reporter includes t h e decisions of the District Courts, old Circuit Courts, and Circuit Courts of Appeals The Supreme Court
reports for later years are similarly cited by the abbreviation U.S. Supreme Court cases prior t o 91 U. S. are usually cited b y the name of t h e official reporter who reported them. Thus 23 Wall. stands for the twenty-third T h e Official Gazette of the Patent Office volume of Wallace’s Reports. is cited a s 0. G. Usually no special page is referred to in the latter. The number of t h e page is given on which the cited case begins, a n d the preposition “at” is omitted. T h e cases in the District and Circuit Courts before 1880 are reported in various publications. Those cited in this essay are either 0. G., Blatschf. or Fish., the latter, respectively, standing for Blatschford’s United States Circuit Court Reports, and for Fisher’s Patent Cases. These cases are usually most easily found in the collection known a s Federal Cases, where they are alphabetically arranged.
-
