December, 1923
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
octahydroretene, and confirmed this by treating the saturated oil with sulfur with which octahydroretene was dehydrogenated, and obtained crystals of retene. Experiments were carried out following Schultze's directions. At first the mixture of Fractions I1 and 111was treated with concentrated sulfuric acid, and saturated compounds were obt,ained, with a yield of about 19 per cent of the refined oil. This saturated kauri copal oil has some resem-
1277
blance to the saturated resin oil which has been described by Schultze, but is quite a different substance because it gives neither retene by treating with sulfur, nor trimellitic acid by oxidizing with dilute sulfuric acid and manganese dioxide; therefore, in order to confirm this composition some other method is necessary. Nothing was learned by treatment with nitric acid or oxidation with alkaline permanganate.
A New Method of Gas Analysis' By Rudolph Geberth 1452
EAST1 7 ST., ~ BROOKLYN, ~ N. Y.
0 OVERCOME objections to the chemical methods of making quantitative determinations of gases, as employed by the manufacturers of commercially used gases, an apparatus has been designed by Samuel Ruben, a physicist, of New York, based upon principles of resonance, by which such determinations as to binary gases are made with great accuracy and speed. Broadly considered, the apparatus involves the principle that mechanical energy impulses, such as sound waves, produced by a vibrating element, differ in character with the condition of the gas through which they are transmitted. By "condition" is meant either a physical property, as density, or its chemical composition.
T
When the column is in resonance with the sound wave length, the load upon the fork is a t a maximum and is sharply so indicated by the ammeter. The dial reading, then, which is in accord with that of the ammeter, indicates the resonance length of the gas column. The accompanying curve shows the relation between the length of chamber and the ammeter readings. (Fig. 2) The resonance length of a known gas is indicated by the relation between the velocity and the frequency of sound through that gas; or the resonance length L is equal to the wave length X of the sound source. =-a
VO =
FIG. APPARATUS FOR GASANALYSIS
The accompanying illustration (Fig. 1) shows the complete apparatus, consisting of a closed cylinder, adjustable as to length, through which the gases are passed, and having a t one end a diaphragm coupled to a tuning fork, electrically maintained, together with a current-measuring instrument. One of the cylinders is closely movable within the other by means of a rack and gear arrangement, and has a graduated dial attached to the gear shaft for indicating gas column length. A thermometer projects into the chamber for temperature corrections. The tuning fork is oscillated a t a constant rate by an electromagnet having a carbon transmitter as a variable resistance. As the column is brought close to the resonance point, the ammeter, in series with the electromagnet, indicates a very sharp current rise. The input current of the driving element depends upon the amplitude of the fork vibration as controlled by the diaphragm, its force of reaction against the fork varying according to the condition of the gas in respect to its resonance length. * Received December 12. 1922
y,x = L
9; V, d1.4$ (1 + =
at) ; V, =
VO 2 / l f a t
where p equals pressure; d, density; a, temperature expansion coefficient, 0.003665; t, operating temperature; VO,velocity a t O C.; f, frequency. As the tuning fork maintains an oscillation of constant frequency, ordinary pressure changes do not affect the resonance length of the gas; but as its velocity varies with temperature, correction therefor must be made. From the accompanying curve (Fig. 2) it may be noted that the resonance amplitude is very perceptibly reduced by a slight variation in the length of column, as indicated by the ammeter, At the frequency employed in various devices, a change of 0.01 per cent from the resonance length causes the column to be thrown out of resonance from the maximum amplitude indicated by the meter. Thus, a change in the density of the
0
4
8
12
16
20 24 28 32 36 46 44 Cenf i m e fers
FIG. 3-RELATION BETWEEN LENGTHOF CHAMBER AND AMMETEX os TUNINGPORKDRIVSRCIRCUIT READINQS
gas sufficient to cause a change in the resonance length of 0.01 per cent is readily indicated; and if the resonance length of one of the gases in the binary mixture is known, its quantitative relation t o the other known element can be determined.
Vol. 15, No. 12
INDUSTRIAL AND ENGINEERING CHEMISTRY
1278
To operate the device, the chamber length is first adjusted to a point beyond the resonance length of the gas to be tested. The gas is then admitted, and when the previous content has been expelled the circuit is closed and the current actuating the fork is noted, the chamber length being reduced until the point of maximum current amplitude is reached. This point is indicated by changing the chamber length in both directions, a sharp falling off of the current occurring in both cases. The dial and temperature readings are then compared with calibrated figures. If the gas is continuously passing through the chamber, a minute or so is required for adjustment, readings, and comparisons. Otherwise, several minutes may be necessary to expel the previous gas content of the chamber. Correction for any vapor present may be made in connection with that for temperature. An instrument is calibrated a t a specific temperature and requires no further calibration. It has no delicate parts and there is little or no wear or deterioration. The current consumption is about 0.15 ampere, thus permitting the use of ordinary dry cells as a source of, energy. The tuning fork is operated a t any voltage between 4 and 12, but a potential of 6 volts is preferable. A specific application of this device is in the determination of the hydrogen content in electrolytic oxygen. Owing to the large density differences between these two elements, a small percentage of hydrogen causes a very perceptible change in the resonance length of the gas column. The difference between the resonance length of a pure oxygen column and of that gas with hydrogen added may be calculated by the equation below, in which L represents the resonance length of oxygen, V
L = -
f
,4rthur Lowenstein Research Fellowship A gift of $2500 a year, for three years, for the purpose of creating the first research fellowship in connection with the newly organized Institute of Meat Packing a t the University of Chicago, has been made by Arthur Lowenstein, vice president of Wilson & Company. This research will be carried on under, Prof. E. 0. Jordan, head of the Department of Bacteriology of the university. Mr. Lowenstein is one of the special lecturers in the Institute of Meat Packing a t the university, as well as chairman of the Committee on Scientific Research of the Institute of American Meat Packers and investigations associated with the packing industry. A series of lectures under the joint auspices of the School of Commerce and Administration of the University of Chicago and the institute has been inauARTHURLOWENSTEIN gurated, and courses of instructions have been arranged so that employees in the packing plants have a better opportunity to fit themselves for their work. The courses are intended primarily for those occupying minor executive positions and who are ambitious to become executives. Both day courses for full-time study and evening courses are announced.
Iff,the frequency, equals 1000 cycles, and V a t mm. per second, L
C . is 317.2
= 31.72~~11.
The resonance length of bydrogen at the same frequency and temperature is 126.95 cm. From the resonance amplitude curve it may be noted that a change of 0.01 per cent in the resonance length gives a comparatively large indication; and as the resonance length varies as the square root of the gas density, a change of 0.1 per cent by volume of hydrogen in oxygen causes a notable change in the resonance length of the column. Therefore, under proper conditions and with correction factors included, it is possible to indicate the presence of hydrogen by a fractional part of 0.1 per cent. The same applies to other gas mixtures, as, for example, air and sulfur dioxide, in which case less than 1 per cent of SO2 is readily indicated. When three gases are present, two bearing a fixed relationship to each other, by determining the purity of one element the percentages of the other two may quickly be ascertained. The cylinders can be electrically maintained a t constant temperature by means of a resistance wire wound around them and connected with a thermostatic control element. This arrangement eliminates the correction factor for temperature and also permits the adjustment of cylinders a t a point from which the meter indicates approach to resonance condition; or the cylinders can be brought to resonance adjustment and any variation from that indication can be noted continuously. For close determinations within narrow limits the entering gas should be dried, as by discharge through a sulfuric acid wash bottle or suitable means. It can also be saturated a t a fixed temperature, in which case a correction factor for water vapor can be introduced.
The packing industry has always been known for its achievements in applied science and prosecution of fundamental research. This work has been done in the individual plants and laboratories, and the establishing of this Arthur Lowenstein Research Fellowship a t the university will be watched with great interest and, i t is believed, constitutes not only an advance in education, but also an important undertaking in scientific research. Evening courses for employees of the meat-pa cking industry are now being conducted a t the downtown rooms of the university. Correspondence courses are expected to follow after January 1, 1924, and a four-year curriculum of day courses will probably be inaugurated on October 1, 1924.
Meeting of Advisory Board on Dictionary of Specifications A meeting was held on October 24, 1923, of the Advisory Board organized to act in an advisory capacity to the Department of Commerce in compiling material for and publishing a handbook of specifications for commodities purchased by federal, state, and municipal governments and public institutions. At the meeting of the Advisory Board, a t which there were present representatives from all but one of the organizations represented on the board, unanimous approval was voted for the proposed plan for issuing in convenient form a thoroughly classified list of all known existing commodity specifications. The board voted unanimously for the creation by the Secretary of Commerce, as chairman of the board, of three committees from its membership to render reports for the approval of the board on the subjects of (1) classification of commodity specifications, (2) form and size of the publication, and (3) scope of the proposed handbook or encyclopedia of specifications.
