Thn purity of sodiiim tungstate is elicckml hy a (lnily analysis on crystals witlidrawn from the filter cach hour. Careful operation requires frequent analyses for tungstic oxide conteiit of the sodium tnngstate solution, acid liquors, wadi waters, and liqriors in tlic recovery process. Tho acidity of the liqmir in the preripitat,ing kettle is folloived regularly, and it has been found that the color of the precipitate is a fairly good indication of tlic excess of acid being used.
tnngsten lakes is a more recent development. The process" consists of mixing solut.ions of a dyestuff, a soluble compound of phospbonis, a soluble compound of tungsten, a.nd an acid in such quantities as to cause the precipitstion of the tungsten lake. Basic coal-t,ar dyes are generally used as the coloring matter. By this met.liod a double salt of tungsten is formed in the presence of the coloring matter without destroying tlic lattcr. It is claimed that tungsten lakes so produced possess a great brilliancy, are ext,remely fast to water, and are little affected by exposixre to light. These lakes arc used in printing and lithogaphing inks and in the manufacture of coated papcrs.
ACKXOYLEDGXENT Tlie authors are indebted to the staff and to F. M. Ilorsey,
direct,or of the Experimental Engineering Laboratory, Kational Lamp Works of the General I.:lcctric Company, for placing tile subject matter of this article a t their disposal. BIBLIOGRAPHY
Pia. 6 - R o i n ~ v DIIDMDRIERN
~ L GUARDS I REVDYED
Before drying a tank of tungstic acid, i t milst pass t( for tilng& oxide content, chloridcs, and residue nonvola 1 e in sulfur chloride. Tlic dcterniinatioiis shomn for tbe iivcrxgc analysk of tunp,stic acid e t a t d under the are made on dried trmgstic acid from each tank.
fJsm OF TUKGSTIC ACIDA
m QOUIUI
TUXGSTATE
Most of the applications of sodium tun8stat.e and tungstic acid are well knowri, 11-'6 bnt thcir use in ,the production of
I-Roscoe and Schorlemmer, "A Treatise on Cl~einisfry."Vol. 11, 5th e d ... 1913, . .D. 1086. 2-Tmnr. Am. Eirdroihcm. Sor.. IS, 601 (1908). 3-U. S. Piitenl 1,335.277 (March 30, l9Z0). I--French Patent 989,040 (April 8, 1908); Belgian Patent 207,299 1AuriI . . 13. 1908). 3--J. Iron Slrrl I?~si.,64, 14 (1903). R--I.'Acndemie Rogale des Sciences, Inscription e t Belles Letties de Toslourc. 1784. 7-Runner end Aartmann. "Occurrence, Chemistry, Metallui~y,and l s e s oi Tengsten," South Dakota School 01 Miner, Ruli. 12 (1918), gives valuable information OD subjecr of tungsten aiid best list ot reiercncer, in. d u d i n s 1917 =nd pait 01 1918S-.Mennicb-e, "Die Metatlurgie des Woltrnmr," 1911,contains a CY%p,ehensive tunerten compaunds, ~~
9-Chmm. Me,. E n g . 2 2 . 9 (1920). 1 W E w i n e p r i n g . 104, 432 (1917). 11-Sei. A m . Ilonihiy, 6, 135 (1921). 12-Amcricon 34nchinist. 60, 99 (1919). 13--Hess, Mineral Resources of U. S. lor 19IR. 1919. 1920, etc. 14-Fink. Mlneial Industries, 1919, 1920, 1921, etc. I5--nrl , J . Wesfern SOC.E a . , 27, 225 (1922). 1~-1, Tariff commisrioo, In(ormrtion Sriies, 279 (1920), 17--U. S. Patent 1,378,882 (May 24. 1931).
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Clarification of Yeast Extracts with Neutral Lead Acetate' By F. W. Reynolds C~reosunnnr>3 LABORATORY, BVIEAUor C m r i s m u , 'U'~sxiuaroa,D. C.
A .\lEl.HOD of pnrification and concentration of enzymeeontaming yeast ext.ract,a employing dialysis or ultrafiltration and acidificat.ion with acetic acid has recently been puhIislied.* \;\lt,h the desire to short.cn somewliat tlic time , experiments on purification have required fnr the pro subseqiieiitly been n e with neut,ral lead acetate. Neiitral lead acetate used in excess has been employed by a number of workers in defecating autolyzed yeast exiract.s, the excess lead being eliminated as sulfide or carbonate and the resulting acetic acid or a.cetate removed by dialy The writer has found t.liat efficient clarifications may be accoinplished by using smaller amounts of lead acetate, such that. no excess remains in the solution to necessitate its removal. The extract may then he dialyzed or washed on an ultrafilter to complete the pnrification. Only enough lead acetate to produce a flocculent, easily filtered precipitat,e need be added. Working with an extract of bakers' yeast,3 it was found that 10 grams of lead acetate per 1000 cc. were suffi*Received M a y 10, 1924. 9 Reynolds. Tnra Jouan*r,16, 169 (19241. I Thc erpciimental work in this connection was done by M. A. XcCaIip.
cient t o produce a flocculent precipitat.e, while 20 grams could he added before lead appeared in the filtrate. With an extract of brewers' yeast the quandities n'ere 25 and 45 grams, respectively. A nredian figure, 15 grams per liter for top yea,& extract and 35 grams for bottom yeast extract, has been used in purifying large quantities, with uniform resuits.* Tlie products of this treatment are practically the same as when excess lead is used and removed or when the dialysis-acetic acid method is employed. S o loss of inrcrtase or melihiase results, and the purified enzymes are stable as far as it has heen possible t o observe. .4 small portion of the lead precipitate, washed free of soluhle material with distilled water, is an excellent filtering medium for the removal of the turbidity or opalescence which may develop in yeast extracts after coiicentration and wauhing on an ultrafilter. It is superior to infusorial earth in that it does not adsorb the enzyme. A bottle containing a quantity of the washed lead precipitate may he kept, with a preservative, in the laboratory for convenient use, only a very small portion being required for a filtration. Prepared z i ~described In reference given in Footnote 2.
