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flat cork of a somewhat greater diameter than that of the bottle and about 3 / 8 of a n inch thick was next selected and a disc a little less than I inch in diameter cut out of i t by means of a sharp penknife, care being taken to cut perpendicular to the surface of the cork and neither to injure the disc nor the ring which remains as the disc must be replaced in the cork after the electrodes and contact strips are inserted. Two pieces of platinum foil 0 . 0 0 2 inch thick, I inch de and 2 inches long were cut, as well as two strips of the same foil two inches long measuring about inch in the center and 3 j i , inch at the ends, cut in the manner UT
Fig. 1.
Fig.
2.
shown in Fig. 2 , D. The strips were each folded over ' in the middle so as t o form a loop, the ends being then fastened between the ring and the disc of cork together with the two electrodes in the manner shown in the illustrations. The tops of the electrodes should come flush with the top of the cork. If the cork has been properly cut, ithe electrodes, owing to the now concave shape, mill :hold firmly in the cork and should be parallel to one :another (see Fig. 2 , A). Should this, however, not .be the case, a short round piece of cork (Fig. 2 , C ) , .previously shaped to fit, can be placed between the 'electrodes and cemented to the cork proper with the .aid of a little plaster of Paris. The cork is now covered with sealing wax on all sides which gives excellent insulation. This can be made smooth by passing a hot, flat piece of steel over i t . A knife blade answers very well. For safety's sake, and to prevent short circuit, should any liquid accidentally get on the stopper between the electrodes, the same is dipped into melted paraffine, the loops being again scraped free. A more finished looking cell can be made by applying plaster of Paris t o the cork after inserting the electrodes, instead of the sealing wax. The plaster can be sandpapered down after drying, giving a perfectly
smooth surface and covering all imperfections in the cork If the same is then coated with black enamel or paint the entire cell has a very neat appearance, Of course the cork must be subsequently dipped in paraffine for the reasons given above. After cleaning the electrodes carefully, the same are coated with platinum black in the usual manner. The opening for the thermometer is most easily made by heating the point of a round file to redness in the Bunsen flame and then applying it to the cork with a slight pressure, thereby easily penetrating through the sealing wax and cork, After this has been done, the opening in the cork can be filed out by means of the same file, until the thermometer exactly fits it, The author made use of a pycnometer thermometer divided into tenths of a degree and reading from I O '-30 Centigrade. The general type of the cell, i. e . , concave electrodes, makes it especially well adapted for use with poorly conducting fluids, the cell constant of the cell illustrated being 0.237 when 2 0 cc. of liquid are used. I n using the cell and for determining the cell constant, 2 0 cc. of liquid are measured into the glass from a standard pipette (always used for this purpose). It will be found that in dealing with the same kind of solution, i. E . , one of uniform viscosity, the cell constant will remain unchanged within the permissible limits of error allowed in technical conductivity measurements, provided of course that the same pipette is always used for delivery. Should one so desire, other volumes of liquid may be used, z i z . , 3 0 , I j and I O cc., the cell constant being determined for each of the respective heights of liquid in the cell. The cell is very easily cleaned, simple in manipulation and not easily damaged. 2 7 3 9 MILDRED A V E ,
CHICAGO
APPARATUS FOR FUMELESS KJELDAHL NITROGEN DIGESTION. B y A. P. SY. Received June 4, 1912.
A digestion with sulfuric acid for the Kjeldahl nitrogen determination is practically impossible unless some provision is made for taking care of the large volume of fumes evolved. Even in small quantities these fumes are so objectionable that complete removal is necessary Many devices and arrangements are known and in use, the customary practice being to conduct the digestion in a good hood or closet connected with an efficient natural or forced draught. Such a n arrangement is often almost impossible and is always expensive, necessitating an expenditure of several hundred dollars when a fan and motor are used. I n addition to the expense, this arrangement is always very noisy, unless the fan is located a t some distance from the hood, in which case its efficiency is decreased proportionately. For a number of years the writer used a hood with natural draught, but on some days i t was necessary to open all windows and leave the room. Many laboratories, especially those of hospitals and physicians, have no fume closets at all and a
Sept., 1 9 1 2
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 .
Kjeldahl nitrogen digestion is out of the question. Three years ago the writer began using a n arrangement similar in principle t o the one here described and shown.
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to the apparatus, allowing the flasks t o be shaken without detaching them. The rubber tubing lasts for many determinations and can easily be replaced. The bulb-tubes are held in position by a special support, allowing their easy removal when shaking is necessary. The bulbs act as air cooled condensers for the acid fumes, and prevent the materials in the flasks from going dry as quickly as when the fumes are allowed to escape. The lower bulb acts as a loose stopper for the flask, while the upper one rests on the support when the apparatus is not in use, always leaving the bulb tubes in position. At the beginning of a digestion, water is driven off, and in order t o prevent its dropping into the hot acid and causing spurting, the supports of the Kjeldahl flasks are so arranged a s to give the latter a slanting position, allowing the condensed water to flow down the sides gradually. I n its present form the apparatus has a quadruple burner on a clamp attached to theironstand,asshownin the drawings. Tooperate, connect the pump with the watersupply and drain, andstart heating the flasks with a low flame. The operation and advantages of this arrangement need no further explanation. The apparatus may be obtained from Eimer and Amend, of New York City. UNIVERSITY OF BUFFALO, BUFFALO,N. Y.
A SIMPLE METHOD FOR PURIFYING DRINKING WATER. By J. L. SAMMIS. Received July 10, 1912.
FIG. 1. FRONT VIEW’.
It has been in constant use in the university as well as the writer’s laboratory, and in its present form seems t o answer all requirements f o r fume absorption. A brief description and reference to Figs. I and z readily explain the apparatus. The whole is mounted on a portable iron s t a n d , occupies but a little space a n d is easily moved. I n . t h e apparatus here shown, four ordinary long-necked 500 cc. Kjeldahl flasks. suitable for FIG. 2. SIDEVIEW. digestion and distillation, are used. The Kjeldahl flasks are supported a t the bottom by a special ring-clamp. Into the neck of each flask there is a loosely fitting bulb-tube with two large bulbs and an elbow bend. These bulb-tubes are connected with a large glass suction pump having four branches. Rubber tubing is used for connecting the bulb-tubes and pump, in order t o give flexibility
Water for drinking purposes is commonly purified on the small. scale by distillation. Distilled water is flat and unpalatable and has to be cooled and stored for use. The possibility of pasteurizing water for drinking purposes, as it flows from the pipes, seems to have attracted little attention. For this purpose, water flowing through a small pipe can be momentarily heated (in a steam jacket or otherwise) to a tempera( 7 9 - 8 2 O C . ) , by which means ture of 175-180OF. disease germs such as those producing typhoid fever, dysentery, etc., are destroyed, while the water under pressure in the pipe does not lose its dissolved gases or its palatability. The water thus heated can be quickly cooled in the pipe, by means of a cold water jacket. I n most buildings, only a small proportion of the water used would require to be heated and cooled for drinking purposes, but the entire quantity used for all purposes could be run through the jacket, to aid in the cooling. An arrangement of pipes for this purpose can be set up by any pipe fitter a t any point where a steam pipe and a water service pipe pass near each other. It is desirable that the steam pressure be uninterrupted, and that the pipe be drained free from condensation. Also the water pipe should be one through which more or less water is flowing continually. The diagram shows the arrangement of the parts. The steam main is cut at A A’, the water main a t B B’, and the cut ends are reconnected through by-passes which constitute the steam jacket C, and the water jacket D, used for cooling the drinking water.
