Dec.,
1911
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
not hesitate t o purchase a n Edison battery, fearing t h a t the battery may not be durable, for one manufacturer of electric vehicles absolutely guarantees t o replace anything t h a t goes wrong in the battery up t o 50,000 miles of travel. The history of the method of development of the Edison storage battery is most interesting. I n answer t o questions of the writer, Mr. Edison stated t h a t all possible chemicals and structure t h a t had been used or could be used for plates and electrolytes were considered a t the outset, and cells were made up one b y one as knowledge and imagination prompted the selection. Every cell was carefully tested and the behavior recorded. He said: “We had as many as eighteen hundred distinct types of cells on test at one time. We did not construct a few cells and wait a year or two for results, b u t crowded into the period of observation experience with thousands of cells.” Finally he said with emphasis: “An individual’s lifetime is far too brief t o attain any marked advance in invention unless he extends his experience simultaneously t o a very wide range of materials, structures and phenomena. An investigator like Luther Burbank has a great advantage over me for he can carry on millions of experiments a t the same time.” The Edison battery is the result practically of the efforts of one man expended almost continuously over a period of eight years and personally directing many thousand experiments which were made. By this I do not mean the battery in a broad and general sense, but I mean the precise mechanical and chemical structure t h a t i t now is t o d a y , and not only ’that, but practically all machinery and appliances used in its manufacture are the results of Mr. Edison’s personal suggestions and supervision. He has had loyal, devoted, and hard-working assistants who have carried out his ideas with enthusiasm, but i t is the Edison battery with which we are now dealing, both in fact as well as in name. I n the years t o come I believe it will be regarded as the greatest monument t o his genius, and if the full story of its development were told, I believe it would represent one of the greatest intellectual accomplishments of all time.
---___ AN ELECTRIC HEATER FOR ETHER EXTRACTIONS. B y WILLIAM H. Ross. Received September 26. 1911.
Many electrical appliances have been devised for laboratory use, but up t o the present illuminating gas, where available, is used as the principal source of heat in most laboratories. This is largely due t o the fact that electricity is ordinarily more expensive than gas, and for many purposes not so convenient, since changes in temperature can not be brought about as quickly in an apparatus heated with electricity as with gas. This is true particularly of electrically heated hot plates, or electric heaters for Kjeldahl work. I n the case of electric furnaces, on the other hand, these disadvantages are n o t so serious. The necessity of bringing about quick changes in temperature is
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not so important, and as the apparatus may without much inconvenience be surrounded with a very thorough heat insulation, a furnace of this kind may be used very economically. A simple furnace for high temperature work has recently been devised by Benner and may be made with little expense. I n a n electric heater for ether extractions the disadvantages already referred t o are still less serious. Owing t o the low temperature required the expense of heating is immaterial, and a uniform, rather than a variable, temperature is desired. Furthermore, a n apparatus of this kind has the advantages of safety and neatness over the gas-heated water bath which is still largely used for this purpose. The heater herewith described has been in use in this laboratory for some time, and has proved very satisfactory both in the matter of convenience and efficiency. The outer part of the heater, which is represented in Fig. I, consists of a rectangular box, 80 X 2 0 X 1 2 cm., made of ebonized asbestos, I cm. in thickness. The asbestos serves the double purpose of lessening the loss of heat by radiation, and does away with any danger of short-circuiting between the wire system shown in Fig. 2 , and the outer box. The box is supported on brass legs, 4 cm. in length. A galvanized sheet-iron box, B, 74 X 18 X S I / , cm., rests on asbestos supports within the outer box, and a t a distance of 2 cm. above the wire system which is supported horizontally on asbestos supports about 2’/, cm. above the bottom of the outer box. The top T of the outer box, which is made of the same material, is detachable from the rest of the apparatus, and has six openings through which the flasks of the extracting apparatus pass, and rest on the bottom of the iron box below. When the current is turned on b y means of a switch, S, a t the end of the outer box, the flasks not only become heated by contact with the iron support upon which they rest, but are surrounded with a heated atmosphere which minimizes the current required t o bring about the extractions. Asbestos covers, C, are provided for the holes which may not be in use. If desired, split covers, SC, may be obtained t o fit closely around the necks of the flasks. These are not a t all essential, however, a s the current necessary t o bring about a given rate of extraction is decreased but little b y their use. By means of the regulating switches SI and S,, the current flowing through the apparatus may be varied from I t o 5 amperes, This is brought about b y cutting out the outer strands of wire as the switches are moved from position I t o position 5 . As the strands are strung in the form of spirals, any expansion which takes place on passing the current causes no noticeable lateral displacement of the strands, but simply causes the coils t o move a little closer together. Any danger of the strands coming in contact, however, is prevented b y separating them with strips of asbestos as shown in Fig. I. Brass rods, R, 11 mm. square and 74 cm. long, lie along the sides a t the bottom of the outer box I
T H E J O U R - V A L OF I - V D U S T R I A L ax^ E S G I X E E R I N G C H E M I S T R Y
Dec., 1911
S,&S U Fig. 1
and serve the double purpose of giving rigidity t o it, and of connecting the electric circuit with the wire system shown in Fig. 2. Owing t o the small current required in making extractions with ether, it was not thought advisable t o provide for heating less than six flasks a t a time. The resistance wire is made of No. 2 2 nichrome alloy which affords a resistance of 0.937 ohm t o the foot. When the apparatus is connected with the I I O volt circuit, the strength of current obtained a n d the length of wire through which the current passes a t
7'4ems.-
-
--
-->
Fig. 2.
each step as the switches are moved from position I_to position 5 are a s follows: Position of switch.
.1 2 3 . 4 5
Number of strands in circuit. 18 14 10
6 2
Total resistance. Ohms. 110.0 73.3 55.0 40.0 27.5
Length of wire. Cm. 3578 2384 1589 1301 895
Current. Amp. 1 00 1.50 2.00 2.75 4.00
I
By changing the switches one a t a time, twice the number of steps in the variation of the current may be obtained. The inner vessel is water-tight and may be used as a liquid bath if desired. When used as a water bath with the top plate removed, the water becomes heated t o a temperature of about 42' with the switches in position I . This causes the ether t o distil a t almost exactly the same rate as when the apparatus is used as a n air bath with plate P in place. When it is desired t o heat more than six flasks a t a time, this can be conveniently done b y removing the top plate, in which case the apparatus can be more economically used as a water bath.
l h e minimum temperature obtained with the top plate removed and glycerine in the inner box is 60'. This increases to 80' with the plate in place, while with the switches in position j a maximum temperature of 13j ' may be obtained. The apparatus as thus described may be obtained from the Central Scientific Co. a t a very moderate cost. * The advantages of the apparatus may be stated as follows: ( I ) The flasks rest on a hot metallic plate, and are surrounded b y a heated atmosphere in consequence of which a very low current is sufficient for extractions with ether. ( 2 ) The temperature of the apparatus is capable of being changed between considerable limits which enables the same apparatus t o be used for making extractions not only with ether, but also with.acetone, chloroform, carbon tetrachloride, and other solvents commonly used in making extractions. The same feature enables the apparatus t o be heated u p quickly a t first then used for making extractions with ether. (3) After the extraction is complete, the solvent may be evaporated from the flasks without danger of ignition by replacing them in the apparatus and turning on a low current. (4) With the top plate removed the apparatus may be used as a hot plate for making slow evaporations, and for other purposes. (5) If so desired it may be used as a liquid bath by placing water, or some other high boiling-point liquid, in the inner box. AGR EXPT STATION. UNIVERSITY O F ARIZONA, TUCSON.
--____ TWO NEW PIECES OF CHEMICAL APPARATUS. C. Apparatus for the continuous extraction of liquids with im-
miscible solvents lighter than water. [I. Apparatus for quantitative reactions which depend on the measurement of an evolved gas. B y R. F. BACONAND P. B. DUNBAR. Received September 26, 1911. I.
CONTISUOUS
LIQUID'
EXTRACTOR.
This apparatus was designed originally for use in the extraction of lactic acid from ketchup and other 'ruit products. Its principal advantages are com-
