AUGUST, 1948
0
A SIMPLE STILL-HEAD REIN0 W. HAKALA Mohawk College, Utica, New York
Tm STILL-AEAD to be described is of
the total-con- A densation, variable take-off type-a type with which the undergraduate organic chemistry student ought to c be familiarized, because of its great usefulness in fractional distillation, but generally isn't, owing to the relatively high cost of the usual unit of this type. The still-head shown in the accompanying illustre tion is fairly inexpensive. The unusual feature of this still-head is its lack of a stopcock. It consists of a T-tube with two long arms that are perpendicular to each other. Each of these is fitted with a microLiebig-condenser jacket, if necessary. An ordinary addition tube, fitted with a thermometer, and with a lubricated stopper to hold the T-tube, completes the en- position Tskm-oE Positbn unit. A-Anmiur renux srm H-Stonper to hold T-tube; with In operation, the still-head is kept in the reflux ~ - ~ t ~ t i ~ ~ ~ hole ~ large ~ ~enough ~ tof allow i ~ ~ position until the temperature of the vapors reaching C-Micr-Liebig-oondemer jacket rotation of T-tube, but snug b e d ahenneoessa,ru) the still-head becomes constant. Then the angular D-Clamp enough to be ~ ~ ~ - t i ~ h t : Lubricated with glyoerol or reflux arm is rotated downward until it is in the take-off E - C I . ~ ~for. in renu. ~ 0 8 i t i 0 ~ S ~ O P C O CEream ~ F C L ~ P for o in take-off Position I-Addition tube position, and a test tube or other vessel is put in place &Thermometer ~ - ~ ~ ~ C Ot I Ui ~ ~ ~ ~ t i to receive the condensate. Then, when the temperature begins to rise again, the angular reflux arm is rotated upward to the reflux (It is best to support the stationary reflux arm with a position and kept there until the temperature again be- 3-pronged clamp. The angular reflux arm should also comes constant. be supported, in both the reflux and take-off positions, The next fractionis removed the same way as before. particularly when i t is fitted with a condenser jacket.)
~
~
~
~
~
