T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y .
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trol requires rapid work. The method has been checked against the other standard methods by Mr. W. C. Markworth and Mr. H. C. Knight, 1st and'znd assistants. CHAS. v. ZOUL. %E
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AND G ~ B I B I-*BO=ATORY, f"onuD*La. 0x10
MPROVEMENT OF THE WILEY METHOD FOR DETERMNING THE MELTING POINTS OF FATS. During the course of an extended investigation on the clmnical and physical properties 01 animal fats the writer had occasion to use the Wiley method for determining the melting point of iats. This exceedingly ingenious method was iound difficult of manipulation under all but perfect conditions. However, with a few modifications the operation may be considerably improved. As is well known to all who have had experience with this method the main difficulty is encountered in securing fat disks periectly lree from occluded air. During the course of the determination, 'the smallest trace of air is sufficient, by its expansion on heating, to carry the fat disk to the surface of the liquid and thus ruin the determination. With high-melting fats, as tallows, the difficulty is especially great on account of the great change in temperature and therefore great expansion of the air. I t is true that the number of air bubbles may be appreciably decreased by preparing the f a t disks on ice floating in cold, recently boiled, distilled water. If the water is not near the freezing point, some of the ice will melt and thus introduce air into the %,at=. Some ice used was iound to be so full oi occluded air that even with these precautions iat disks prepared on i t invariably were found to be useless ior a melting point detwmination. With a view of correcting these difficulties the writer prepared f a t disks by dropping the melted fat on cold mercury. By proper adjustment of the height from which the iat is dropped, together with proper control of the temperature ai tlie fat and mercury, disks of very regular shape were obtained. When thoroughly cool and hardened, they were removed with a cold steel spatula and thro\r.n into a beaker containing cold, dilute (50 per cent.) alcohol. The beaker was tlien set in a vacuum desiccator and the air exhausted until bubbles ceased to be given off. Usually this was obtained in less than an hour. Disks thus prepared were iound to be always free from occluded air and satisfactory in every n a y for the determination. HARRYSTEENEOCK. UBO-TORY OF A O ~ I C U L T U X ~CXEMxSTRY. L UNlYIiilSiTY OF W5SCONSIN.
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cury expands. A consists of the magnet coils of an old worn-out electric bell. The soit iron bar of the bell was soldered to the end of a single kniie switch, os short as possible, and iour dry cells connected with the capillary tubing and coils. all in series. One set of lamps, put in staggered (all sockets on one side can be seen in cut), consists of four 16candle power incandescent lamps continuously on, while the other set, for our use, three 16 candle power and.one 32 candle power, is connected through the kniie switch. The wire in the capillary tubing can be so adjusted that when the mercury expands to the desired temperature, the battery circuit will close, the magnet will attract the soit iron (that is, throw out the switch) and the other set of lights will go aut. When the w e n cools below the desired temperature, the mercury falls, the battery circuit breaks, and when the switch engages again (instantaneously), the lights go on. Two I" angle irons are fastened to the inner sides of the oven, forming a support for the oven shelf, which should be of thin iron and contain plenty oi holes for circulation. TIE lamp sockets (S) extend through the oven and are made of porcelain. The door (D) is of same material as rest of the box, and is fastened with riveted hinges. Two I" openings are left in top lor
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A CONVENIENT DRYING OVER. To some of the younger chemists in small laboratories, who have had trouble in finding a satisiaactory drying oven ior various temperatures, this device in use in onr laboratory may have some suggestion. We makc no claims ior originality in this device, and the ideas were suggested from various sources and concentrated in this oven. It consists of an oblong box "0" as shown in the thick. The box itself is made of cut 12" X 12" X 18" x two thicknesses of thin black sheet-iron with P transite asbestos board (obtained from Xi. W. Johns-Manville Co., of Detroit) between. All joints are bent and overlapped so that rivets or other fastenings are unnecessary. The oven is heated by electric lights in two circuits, one set being on continuously, and the other connected through B homemade thermostat device. The thermostat consists of a piece of fine capillary tliin bulb, glass tubing.(B) about 8" long, with a %" to blown on one end, and full of clean mercury. A small piece of platinum wire is sealed a t this end, and another piece of wire i s thrust in the other open end, lo close the circuit as the mer-
thcmmoAeter (T), tliermostat (B) and vent. Care must be taken to have the kniie sixitch as light as possible to work quickly witbout doing too much mechnnical work lo compromise accuracy of working, and the bore oi capillary small enough to allow considerable expansion for each degree of temperature. This makes a very satisfactory automatic oven, and will run very close to the desired temperature, depending on the skill in glass-blowing and adjustment of switcli. A thermometer which we purchased specially constructed to cut OK a t 9s0 did not work as delicately as our awn device. Any temperature may be obtained easily up to rgoO C., dependingon tlie number oi watts consumed. We happen to use 95' C. wit11 a maximum variation of about one degree each way. A t 105' to iro' the variation is niuch smaller. The cost of tlie whole of this oven, including labor, was below $ia.oo. The wriicr happens to know of no satisfactory automatic device similar to this on the market, and has Seen none in the literature. There are no resistance coils to get out of ordcr or burn out, and when the lights burn out it is only necessary to replace them by screwing new ones in the socket. Another, but not as satislaetory a
