INDUSTRIAL AND ENGINEERING CHEMISTRY
324
Table V. Precipitation of Gnmsnivm with 5,6-Benzoquinoline Ge01 Found XL7.
Ge01 Taken
Mo.
Mg.
MU.
843 54.2
84.2 54.0
49.9 49.8
49.8 50.1
Ge01 Taken
GeOi Found
5,6Benaoquinoline would appear to be a superior precipitant for germanium for the fallowing reason?: The precipitation procedure is simple and yields a product of very high molecular weight. The crystalline precipitate is easy to filter and wash and there is accordingly little danger of contamination by foreign ions. TM: precipitate is readily converted to germanium dioxide. A specimen of 5,fi-benmquinoline trioxaJatogermanate was purified by recrystallization from water. Weighed samples were ignited to the oxide and from the loss in weight 8. ratio of 1.98 males of base for each mole of germanium was edouleted. B e es,uuse B definite composition was indicated, an attempt was msde to preoipitate the derivative in pure form and to weigh it directly. In all these attempts some of the reagent was copreeipitated, even when its concentration was reduced to the point where quantitative preoipitatian of the germanium was no longer obtained. The precipitate was also found to lose weight slowly i n s desiccator and to come to a constant value only after 30 hours. A concentration of 20 to 30 grams of sodium chloride in a vol-
Vol. 16, No. 5
ume of 400 ml. completely prevented precipitation of this derivstive. I t would appear that the germanium is firmly bound in B complex ion of the type &CIS-- under these conditions and there fore fails to form the oxalate complex which is necessary for precipitation. Of the other members of the fourth periodic group, titanium, zirconium, and tin are known to form complex oxalates. 5 , 6 Benzoquinoline was found to give a precipitate when solutions of these elements were treated by the same procedure as was used for germanium. The precipitate formed with tin resembles that of germanium very closely, while the products obtained with titanium and sirconium appeared to be much more insoluble and flocculent in nature. These compounds are being investigated. INTERFER~NGSUBSTANCES. All elements which form insoluble oxaltLtes when treated with oxalic acid must be absent. Titanium, zirconium, tin, and to a lesser extent, iron, form complex oxalates which are precipitated by the reagent.
(1942).
(4) Willard. H.H.,and Zuehlke. C. W.. Ibid., 65.1887 (1943).
FROM a disiartation avbmitted by C. W. Zuehike to the Graduate Bohool of the University of Miahigan in psrtid fulfillment oi the reqvirernents ior the demee of doctor of philwmhyin ehernintry
Support for Kjeldahl
Flasks
JACOUELINE FRONT, Mellon Institute, Pittrburgh, Pa.
BECAUSE
of their peculiar shape, with round bottom and elongated wide neck, Kjeldahl flasks do not fit into any rack ordinarily found in a chemical laboratory. Tall rectangular supports have been used with clamps holding the flssks, but such arrangements are unstable and working the clamps is ineonvenient and time-consuming. I t is considered desirable to have a support which will grasp the flask, hold it firmly, yet release it with one movement. Furthermore, it should hold the flash vertically, snd provide easy access to each f l a s ~ as , samples are measured into them.
The necks and lips of the flasks me not uniform in 8128; there fore, the holding device cannot be rigid if it is to accommodate these differences. To salve this problem in this laboratory, a holder of simple design has been made, The beveled openings are provided with B spring (see drawing). The fiberboard (or plastic) disk has s k places for flasks, slthough any number can he used. This disk is constructed so that it rotates on a central shaft and each flask is equdly accessible. To stabilize the support, a heavy circular base of metal is employed, with a diameter of 35 em. (14inches) extending out as far as the widest part of the hanging flask. The upper portion of the neck of the flask is pushed into the disk opening. so that, when the flask drops down, it catches on the bevel and is held firmly by thespring about 1.25 em. (0.5 inch) below thelip. Toremoveaflask from the rack it is merely necessary t o raise it straight up and slide it out. This stand is very useful ' ' dding the flasks while >rsolid or liquid samare measured into I. It is substantial Igh to support several ml. Basks and their ents with no tend' to tip. Ammonia u..dlations and nitrogen digestions have beenfaciiitated considerably by this inexpensive and easily constructed support.
