T H E JOCKA\-dL OF I A Y D C S T R I L 4 LA,VD E.YGI.YEERIA-G
46
of Arizona. where gas is $1.50 per 1000 cu. f t . , it costs about I . j cents per hour to run a Bunsen burner. Therefore, when, as is the rule, several ignitions are to be made, the electricity is considerably cheaper than gas since 2 t o 4 crucibles can be ignited in the smaller furnace and 4 t o 8 in the large. In these electric furnaces, temperatures can also be reached in a porcelain crucible which are rather difficult t o obtain by means of a Bunsen burner or blast lamp.
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CHEJIISTRY.
J a n . , 1912
and installed by a local tinner at a cost of $21.00, not including the steam trap. I n operation the still is charged with 35 pounds lump lime and 26 liters of ordinary 94 t o 95 per cent. alcohol. A current of water is started through the condenser and steam turned on until the alcohol has been heated t o boiling and then turned off. This takes about five minutes’ time and the dehydration of the alcohol once started evolves sufficient heat to keep the still hot some hours. To insure the completion of the dehydration, the steam is turned on the next morning and the heating with the condenser vertical continued for six or seven hours. The union A is then loosened, the condenser turned down into the nearly horizontal position shown in the sketch,
t
The heating and cooling curves (Figs. 4 and 5 ) , taken with the door closed and open, show the rate a t which the furnace will heat up and cool down. With ordinary usage, furnaces, made as described above, have a life of several hundred working hours and when one burns out i t is only a matter of the expenditure of a few moments of time to renew the heating element. UNIVERSITYO F ARIZONA, TUCSON.
A STILL FOR ABSOLUTE ALCOHOL.: By RALPHH. M C K E E .
Received October 1 7 , 1911.
I n a laboratory, in which considerable organic work is carried on, the expense of absolute alcohol in a year’s time is a distinct item. The still shown in the accompanying sketch has proven efficient in the preparation of absolute alcohol from ordinary 94 per cent. alcohol. I t is made of sheet copper tinned on one side, with a half-inch bent brass pipe (32 inches within the still. A greater length would probably be a n improvement), whose upper end is connected with the main carrying steam a t about 40 pounds pressure and the lower end with the same steam trap used for our still for distilled water. An opening, B, four inches in diameter, is used for filling a n d emptying the still. I t is closed by use of the top of a plumber’s drum trap such as is commonly used in connection with bath tubs. The still was made Another form of alcohol still is described by Warren. J . Am. Chem. Soc..
32, 698
(1910).
the union tightened and the distillation and collection At this point it is necessary to wrap some kind of a blanket about the body of the still, otherwise, owing t o air cooling, the distillation will be slow and incomplete. To clean, the unions are opened and the still removed to a convenient place and washed out b y use of a hose inserted into the four-inch opening B. The yield is somewhat over sixteen liters of alcohol of slightly better grade (99.8 per cent.) than shown by freshly opened bottles of “absolute alcohol” from two well-known German chemical houses. The cost of the product is about $0.30 a kilo as compared with the ordinary purchase price of $1.10 a kilo, both being on the “duty-free” basis granted to educational institutions. Laboratories which cannot avail themselves of “duty-free” straight alcohol may find it worth while to prepare, by this apparatus, water-free alcohol from the ordinary denatured article.
of the absolute alcohol begun.
JfAINE. ORONO
UNIVERSITY O F
