ABSTRACTS TEACHING METHODS, AIDS, APPARATUS, AND WGGESTIONS Commercial Material for Science Classes. ANON. Sci. Class~oom,8, 12 (Dec., 1928); 8,12 (Jan., 1929).-In THISJOURNAL, 5,1350!0ct., 1928) we printed an abstract under the above title from the Sept.. 1928 issue of Sncnce Classroom. Corrections t o that list have been published as follows: "The Duriron Co., Inc., Dayton, O., does not supply exhibit material for classes." (See Correspondence, THISJ OURNAL, 6, 151 (Jan., 1929). "The Crucible Steel Co of America, 17 E. 42nd St., New York City, does not supply material for high-school chemistry classes." "Vacuum Oil Co., 61 Broadway, New York City, does not supply material for high-school chemistry classes." Additions to Lists of Firms have been made as follows: Abbott Laboratories. North Chicago, Ill.; Aluminum Wares Association, 844 Rush St., Chicago, Ill.; American LaFrance and Foamite Corp., Turner St., Utica, N. Y.; Calumet Baking Powder Co., Chicago, Ill.; E. I du Pant de Nemours & Co., Wilmington, Del.; Merck and Co., 45 Park Place, New York, N. Y.; Rayon Institute, 250 Fifth Ave., New York, N. Y.; M. W. G. Standard Oil Co., of New York, 26 Broadway, New York, N. Y. Dufton Distilling Column for Preparation of Ahsolute Alcohol. W. A. Noyes. I d Eng. Chem., 20, 1190-1 (Nov., 1928).-A simplified apparatus, using the Dufton distilling column, is described. IIn explanation of the cut reproduced:
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A-15-liter copper boiler for untreated alcohol B s t e a m coil of galvanized iron pipe C-brass tube dosed a t both ends D-annealed copper rod, forming tightly-fitting spiral within the copper tube as shown E-brass reservoir, containing anhydrous CaCL F-hrarass tubing through which alcohol vapors enterE G U - t u b e , enabling inspection of CaC4 solution as i t runs from reservoir H-copper coil through which cold water runs slowly, causing the condensation of a small amount of alcohol, and controlling the downward flow of the solution I-worm for condensation of treated alcohol.
Directions for operation of apparatus are included. From 10,000 cc. charge. 9500 cc. of 99% alcohol are obtained. By redistillation, i t is claimed that 99.7% dcoM. W. G hol may be obtained. Reflex Furnace Reduction of Oxides. R. SAXON. Chem. Age, Metallurgical Section, 19, 27 (Ocf. 6, 1828). -"In the ordinary way, using a cast-iron prpe instead of combustion glass tubing, a temperature high enough t o melt brass may be attained using the blowpipe. When the whole pipe getssufficiently hot, a silica boat may be introduced containing the oxide, and coal gas sent through. This heated gas readily reduces copper, cobalt, nickel, iron, lead, and bismuth, and, together with carbon, antimony. The best farm of carbon is that in paraffin wax. A boat of this in the end of the pipe where the, gas assists the coal gas. Some, of course, 1s mlxed enters distils by heat and with the oxide. "For the more refractory metals, arrangements have been used t o render the flaple issuing from the pipe a ~ u n s e n . Use is made of long hood bent U shape, prolecting beyond the end of the ~ i p eand , lifted from it by cmled wire netting. A floor of asbestos is fitted in the end, reaching t o the pipe end. This slopes to allow the play of the blowpipe under a crucible held so that its top is played upon by the flame from the pipe, while the underside may be reached by the blowpipe flame. The use of the blowpipe takes away the luminosity from the pipe flame, and its heat is reflected from the arched top into the crucible itself, without the possibility of air entering. There is no necessity t o use alid. Two blowpipes may be used, one on either side of the crucible, the coal-ffas flame
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playing between them. Such an arrangement makes it impossible to use h k e d clay crueihlcs, which expand and crack. C a l c i r d clay, thin ones, are btst. but their pon:r m w t he closed hv roastine them after coatinz with rcsin. shellac. or aluminum oalnt. This fills some of.ththeir PO& with carbon, whkh does nod. For preliminary erperirnerttr thin calcmcd smoking d a y s are better t h m anr othvr form of~mucihlr The >tern forms nn 0 1 ~ 1 1 ~for 1 Jmllling wax and gas and finally rluies up i'hr caustic putash dues n,t attack it car it d w r silica, and one i i
Longitudinal Section.
End View.
not afraid of eivine it eenerous heat on account of its cost. Thick ones invariablv crack under t& heat. "A determining factor in a number of reductions has been the tendency of lime t o form calcium carbonate, even under roasting conditions. This was the lever used formerly t o reduce potassium from t h e carbonate. For this reason crushed calcium carbide is employed in reducing manganese, chromium, zinc, magnesium, and aluminum from their oxides, and cadmium, iron, and copper from the sulfides. The manganese decomposes water rapidly. Taking aluminum as an example, the following reaction takes pla3CaC2 3A1203 = 3Ca0 6CO 6A1,
+
+
+
and although the carbonate does no1 rpprar here, it docs with loww temperiltures. The mrhotl monoxide can he seen burning a t the mouthpiea rnd uf the pap? The whole 8s nut mto wntrr to e r t rid of sur,dluous carbide 2 n d lme. \\'hen thrown into acid suffi&nt t o deal w i t h t h e undewmposed oxide, effervescence, or the lack of it, is an indication of ~nobablt.succes\ or drcidrd failure ns the cnsc may he. On n larger scale the gas may bv identified ;r>hydrogen. If t h carllidc and u n x be roa*lrd togcthrr no carbonxe result%.nor r m rflrrvr.;cence h r obtnmr.d with a r i d The nreseuce of bubbles of gas, therefore, is a good suggestion of the presence of the metal." ' The arrangement of the apparatus is shown in the accompanying diagram M. W. G. A Practical Apparatus for Determining Molecular Weights by the Boiling-Point Method. H. RWE ANn N. WASSLIEFP. Helu. Chim. Ada. 11. 713-6 (1928): The Analyd. 53, 510-1 (Sept.. 1928).-The apparatus described is a'modific&on that of Washburn and Read ( J . Am. Chem. Soc., 41, 729-31 (May, 1919):-"The boiling vessel a test tube of mod oualitv. about 190 mm. lons and 31-32 ~ - - consist< ~ ---~- of ~-~~ ~~.~ - - - - mm. - -~wide. and having sealed t o it, somewiat hhow fhe m o n t h a n inner, open-ended jacket,^: 70 mm. in length. the space between the two tubes being 1.5-2 mm. Just below the tup of the inner jacket i s = side tube, B , cunnecterl with P smdl cond~nser,~C, by 9 round joint. The murr imponant pan of the apparatus i* a tube I ) (Figure 2,. 130 mm h?gln. iunnrl shaucrl at thc ha.;?. standine on thrrr fcpt. and brunched at the ton to form thrrr tubes with-somewhat narrow orifices. The shok thermometer. E, such i s is used with the Landshrrgcr al,lvaratuq, reads tu 0 05°C. and is hchl I,).
