1
Abstracts
APPARATUS, DEMONSTRATIONS, AND LABORATORY PRACTICE A simple apparatus for distillation of mercury. M. KLEIBER. Science, 75, 196 (Fcb. 12, 1932).-A simple apparatus is described which is said t o disk1 25 cc. of mercury per hour and is vapor proof. I t consists of a pyrex distillation bulb h (see sketch), attached to a U-tube. Bath the lower end of the U-tube and bulb are attached to 3 mm: barometer tubing. Each barometer tube .is placed inside of the larger tube (sketch). The tube on the left contains impure mercury; the right tube has an outlet t o the receiver. The distillation bulb is heated electrically by a simple coil of resistance wire (320 watts was used). Wire is wound from the mercury level t o the top of the U-tube. To begin distillation suction is applied a t s (from small filter pump) so that mercury rises in both tubes. When the mercury level reaches the resistance wire the current is turned on. After distillation has proceeded for few minutes the pump may be disconnected and the tube r sealed off. G. H. W. A new air drier for analytical balances. E. L ~ W E N STEIN. Ckem.-Ztg., 56, 27 (Feb. 13, 1932).-In order to get accurate results when weighing i t is necessary t o get not only a good temperature equalization between the substance to be weighed and the interior of the balance but also a uniform and low aqueous tension of the atmosphere and of the substance. If the object had been dried in a desiccator and the air in the balance is not dry, moisture will deposit on the object and thus lead to inaccurate results. The vapor pressure of the drying agent must not be lower than that of the substance. Phosphorus pentoxide may sometimes remove molecularly combined water in addition t o absorbed moisture. Calcium chloride and sulfuric acid which are &mmonly used have certain disadvantages. The former tends to form lumps a t the top. These lumps are not drying agents any more and in addition prevent the access of moisture to the lower fresh layers. The upper layer of concentrated sulfuric acid will soon be covered with a thin layer of diluted acid which naturally has a higher vapor pressure than the concentrated acid and the substane to be dried, and hence, deposits water onto the substances instead of removing it. The new perforated air drier (shown in the figufe) which is filled with siliw-gel does away wlth the disadvantages stated above. The pieces of gel have a diameter of 2-6 mm. They can be regcnerated by heating in a current of air a t 13CL150'C. The gel absorbs 23% of its weight of moisture without structural alteration. The drier proper is perforated and is ordinarily kept in the balance case. When not in use for a period of time i t is placed in the box. The drier can also be used t o dry air in various other piems of L. S. apparatus. Anti-bump laboratory glassware. Ckem.-Zlg., 56, 137 (Feh. 17, 1932).-When using ordinary beakers and flasks there often occurs a delay in boiling and the subsequent well-known "bumping." Glassware is now on the market in which this cannot occur. I t is particularly useful in distillations with and without vacuum and in nitrogen deL. S. terminations. A vacuum technic fdr the chemist. K. HICKMAN.5. Frank. Inst., 213, 119-54 (Feb., 1932).-A communication from the Kodak Research Laboratories. It discusses 1127
1128
JOURNAL O F CHEMICAL EDUCATION
JUNE,1931
vacuums. and what constitutes a food oecuvm as considered for each operator; applicationc of vacuum in chemistry, vacuurn disiillationn in the l;xl,or.~trry:various 1ypt.a of lractiunating coltlrnrls, rctenrion and mea.llrcrnc:rlt ol low pressurcc; vactlunn :~s,cr:lt,lier. and vacuunl punlps in ilal~lr-sr!bstnncri. anrl st~h.;tanceswhich bccorne culorcncu l thr itn~d.!nt. lh:rurd> show that " matwing in one or more me&l processes may nzt safely he an index i f concomitant maturity of all. Particularly is this true with reading habits. For instance, failures in collcrr. scirnc2 have bcm. nn a surprising nutnber of instnnccs, shown m be due directly ro lack or abtlity in rmding. hlarny science rrachrrs have in.plicitly ncsulllvd that thc imuortant "Lirctivez oi science tr3chine twre so C~OSCIY COTTCIRIC~ with inforn:ntion tllal an;nfarmatidn test would measure theachievement of other objectives as well a s that of fnct, nr!cl pr~r.riplcs. Prufeiiur kalph Tglcr of Ghlu Stete i);~tvcrsttyh . 1 ~shown rhr. corrrleliul~of irl~icven~unt in inforrnjtton in rooloy) toability to infer in zoc,lopy to bc: as Ion as 11 2!I. There arp. it aeenas. at least twu kirlds of hvrninr i n scirner. Xlav there be still others? Other'studies &e cited which indicate that ittentian t o metGods of study, methods of class work, methods of testing are important factors in determining collvue stodcnt success College te.lcherfare not as a rule given to experinlrntaticm wit11 thesr clazrrs in tearlling or lcarnirtg pruc?s.;r> 111 fnrt, they are very likely to locrk uith diciavor unon arw Jrrvanur,. frclt~ltllc trad~tiorlalin such [ratters Thew anta~urli*ruto large rlns*;.s and decreased lahorltory work ill the scienecc *re cased in illurtratl;;n oi thi5. Recumiring this fact the author suggests thr nerd tlrilt rucll stodicr sllc,t~ldLe.attexnpted for 11:etn by such oryar!>r
