APPARATUS, LABORATORY PRACTICE, AND DEMONSTRATIONS A Simple Individual Hydrogen Sulfide Generator. L. K. YANOWSKLChcm.Analyst, 19, 5. 17 (Sept.. 1930).-The diagram shows the construction of a hydrogen sulfide generator which, due t o its cheapness and ease of construction, is suitable for large laboratory classes. A is a Gooch crucible with a larger opening in the center through which the glass rod B, with a h n g e on one end, is inserted. The FeS is placed into the a u a b l e and can he lowered into the dilute HCI or HZSOIuntil the hottom of the crucible is just belaw the surface of the a a d . A little vaseline on the rod B makes i t easier to work and 1 11 I makes it aas tight. The gas flow- tops "cry
n
shunlynfter raiiingthe cnlethlr a ~ .~ ~If de*irt:cl ~
.'
p i n c h c o c k may be placed on the outlet, in which case a thistle tube should be introduced thmueh a third hole in t& rubber D. C. L. stopper t o act as a safety valve. A Simple Pump for Air under Low Positive Pressures. R. C. BRIMLEY.J. Sci. hzstl., 7, 329 (Oct.. 1930).-"An ordinary filter pump is connected t o an aspirator bottle as shown, so that the stream oeair and water separates out, the air leaving by the delivery tube A and the water flowing t o waste through B. The maximum pressure depends on the height of the waste-pipe B hut can be regulated byaconstant head blow&, if necessary. The rate of air flow must not exceed about one liter per minute which is almost the capacity of the filter pump. Excess air escapes through B with the water. The device will operate for long periods without attention and is quickly fitted up from apparatus on hand in the laboratory." R. L. H. An Improved Volumetric Flask. W. NORMANN. Chem.-Ztg., 54, 744 (Sept. 24. 1930).-The adjusting of the temperature of a solution within an ordinary volumetric flask is a tiresome but necessary task for the preparation of carefully made standard solutions. This can be avoided if a volumetric flask, calibrated not for one particular temperature but for a whole range from 10-30% is used. Instead of adjusting the temperature of a solution i t is only necessary t o determine i t by means of a thermometer and then t o fill the flask t o the proper mark. These flasks are manufactured by A. DarL. S. gatz, Hamburg, Germany. A Convenient Form of Gas Combustion Pipet. E. W. R. STEAUE. J. Am. Chm. Soc.. 52, 2811 (193O).-Advantages claimed: sturdy construction; no leakage; time of combustion shortened; adaptable t o various volumes of gases. Drawing. W H K
A Capillary Gas Valve. H. N. ALYEA. 3. A n . Chern. Soc., 52, 19367 (May. I930).-Description, with drawings, of a device useful in withdrawing extremely small samples of chlorine from a storage bulb. Might be applied in any case where the gas is H. H. K. easily liquified. A Simple Electrically Controlled Thermostat. J. A. CRANSTON.3. Chm. Soc., 1458-60 (June. 19303.-Description with drawing. Compactness and economy in use J. W. H. of electric current are claimed for the thermostat described.
VOL.8, No. 1
ABSI'RACTS
An Electric Heated Thiel Tube. J. D. BmCHARD. Ckem.-Analyst, 19, 23 (Sept., 1930).-With the m e of the Thiel tube in meltine-ooint determina~ u n & buGer-may b; troublesome, especially when the apparatus is t o be housed in to avoid air drafts. The diagram shows a cheap and efficient means of heating. The resistance wire, having a resistance of about 2 ohms per foot, is wound around the tube on a s i n ~ l elayer of isbeitor pdper a t the p o ~ n t sindicated. W ~ r cfrom an old heattn): element may he uttli,ed. \\'hen connrcted tu a Illl-volt nltrrrmtinr c u n w r . tt should draw about 3 to 4 amDeres, reaniri& about.20 feet of the wire. A wide timperatuk ra& can be nttaintd by usmg a variable rcsidancr. A ituppcr uf trm4cnsbestos hoard csn Ile made by turning it rlorn on a I ~ t h e . This dues not clmr or chi^. With a snltsulfuric acid bath temperatures up 'to 380" can be D. C. L. reached. Phosphoric Acid for Determination of Melting . Eng. Chem., A n d . E d . , Points. F. D. S N E ~ Ind. 2. 287 (July. 193O).-If S ~ ~ D ~ hVo s ~ h a racid i c is used place of sulfu& in melki-ng-paint determinations between 10&3OO0C., hand stirring can be avoided. The anoarntw with attached m.-o. tube is set uo as
in
sbout 1 0 0 ~ ~ BY : placing theburner a little t o one
is stirred in below 100". and i t is re& far use. I f heated higher more water &added. D. C. L. If contaminated by organic matter a crystal of KNOs is added. The Preparation of Powdered Sodium. R. E. DUNBAR. Chem.-Analyst. 19, 5, 6 (Sept., 1930).-Finely divided sodium for usein Claisen's, Wurtz-Fittig's, or similar reactions can be readily prepared by this method: A round-bottom Pyrex flask is provided with a n air condenser about 75 em. long. The sodium is freed from incrustations and oil and the desired amount cut into pieces so theflcan be slipped into the flask. I t is then covered with xylene and heated with an electric heater until the sodium is completely melted, m. p. 97.5'. Any vaporized xylene is returned t o the flask. When melted, the flask with condenser still attached is shaken vigorously, breaking the sodium into fine globules which have hut little tendency t o combine on cooling. The xylene and sodium can beseparated by filtration on a Bochner's funnel. The small amounts of D. C. L. adhering xylene are usually not objectionable. The Technic of Copper-Pyrex Tube Seals. H. W. B. SKINNERAND J. H. Bunnow. I. Sci. Instr., 7 , 290-1 (Sept., 1930).-A method for sealing copper tubing to Pyrex glass tubing is given. Since the glass has a coefficient of expansion only ahout one-half that of copper, the glass always cracks away from the copper upon cooling This was overcome by placing a layer of glass inside the copper as well as outside Illustrated. R . L.H. AN11 J. K . PARTISCTON. The Preparation of Anhydrous Oxslic Acid. E.I. JUIINJON 3. C h m . Sor.. l>llI -1 Jurw. 143l . -"Auhyrlrom oralic acid 1s readtly prtpnrrd Ly the followinr m d o d . A mtxtlrre of 5 g. of t h r hydratcd wid n.tt11 111I cc oi tul~~enc. previously &$till4 ovcr calcium chloride, is d i d l l r d in a witlc-r~e~ked ~ m i c a lRxsk until ahout 15 cc. of liquid remain. T h e contents of the f l m b a r t vlhrnnrud tu filtration and the sulid is wh,brd with a little drv Lcnzunl:. I t is thvn krvtin a racumnclr:iccator over wax for 12 hours. The produc? is found by titration to be pure anhydrous m n l i r x i d . A cunic;$l tlnsk is used since, during dritillat~orr,the Anlldrous acid S e w ratcs in small n c d l r %wh~cl.ndhrrr.to tlwstdesuf thedarkandnredificult tr~rrmorefrnm a~~~. n ordinan. Thr method is o r o h h l r calmLIe of almlicariun. with suit, distillinu rlask. able distilline liauids. in manv other cases a i d a n .%
