1384
ANALYTICAL CHEMISTRY
Boats can be constructed from glass tubing of the size desired. They are joined together,rather loosely by platinum wire, so that all stand upright on the table while being filled-0.5 to 0.75 inch of wire should be allowed between each boat. Samples are weighed and transferred quantitatively to the desired boat. A borosilicate glass weight is attached to the lowest boat to overcome the initial buoyancy effect or, instead, the lowest boat can be weighted. After the head has been attached to the proper round-glass joint a t the top of the reaction cell, the glass fiber taread is unwound until the series of boats may be attached to it. The thread is then rewound, and the samples are stored in the upper part of the cell until needed. The samples should be kept sufficiently high in the system so that solvent does not condense on them. The time required for complete solution depends on the solubility of the salt and the degree of stirring. Soluble salts such as ammonium nitrate can be dissolved completely and evenly in liquid ammonia within a few minutes. Samples of extremely small size may be prepared by adding measured volumes of dilute solutions of the salts to the boats. The solvent can be carefully removed by drying or evacuating, thus leaving the desired amount of material in the boat. This method of addition is limited to nonhygroscopic solutes In this laboratory it has been applied to liquid ammonia systems, but it should be equally applicable to other systems.
tube was developed and has been used for approximately 2 years with satisfactory results. The stability tube with foam breaker illustrated in Figure 1 comprises a 25 X 200 mm. sample tube attached to the inner part of a 29/42 standard-taper joint, and an aeration and defoaming device attached to the outer part of the joint. The foam breaker is the outlet tube. Air leaving the apparatus passes through the 1-mm. opening, C, in the foam breaker. Any foam that is produced as a result of aeration is forced through the 1-mm. opening into the relatively large bulb, D, where the bubbles collapse and permit the oil to drain back into the sample tube. LITER 4TURE CITED
(1) AMERICANCHEMICAL SOCIETY, Committee on Analysis of Commercial Fats and Oils, IND.ENG.CHEM., ANAL.ED., 17, 33640 (1945). ( 2 ) King, A. E., Roschen. H. L., arid Irwin, IT.H., Oil & Soap, 10, 105-9 (1933). (3) Riemenschneider, R. I$-.,Turw, J.. and Speck, R. M., Ihzd.. 20, 169-71 (1943). (4) \\-heeler, D. H., Ibid., 9 , S9-07 11932).
Simple Flask for Titrations under an Inert Atmosphere. J. L. Myers and Percy Fainer, Chemistry Wing, Canadian hrmament Research and Development Establishment,Quebec,Canada flask was developed primarily for carrying out titrations T with titanous chloride. Its main advantage is the elimination of the cumbersome lengths of rubber tubing normally used to HIS
Stability Tube with Foam Breaker. Gordon S. Fisher (present address, Naval Stores Station, Bureauof Agricultural and Industrial Chemistry, Olustee, Fla.) and Nelle J . Morris, Southern Regional Research Laboratory, Xew Orleans 19, La. an investigation of the keeping quality of peanut butD ter, crude oils extracted from this product and from raw and
connert the titration flask n-ith the source of carbon dioxide. '%o
GROUND GLASS JOINT
URING
roasted peanuts were subjected to the active oxygen method for the determination of the stability of fats and oils (1, 4). In this method 20-gram samples of oil are aerated at 97.7" C. B 5 mm. in 25 X 200 mm. t u b e s . When the method was applied to crude oils extracted from peanut butter and peanuts, foaming occurred to such an extent that most of the oil was carried out of the tube with the air s t r e a m b e f o r e the determination could be completed. Neither use of the a i r - o u t l e t tube described by King, W Roschen, and Irwin Figure 1. Stability Tube with ( 2 ) nor use of the Foam Breaker a e r a t i o n tube deA . 25 X 200 mm. sample tube scribed by RiemenB . Foam breaker C. 1-mm. opening schneider, Turer, and D. Bulb approximately 60 mm. in Speck (8)overcame length E. Tube approximately 20 mm. in the difficulty. In length with tip drawn to I-mm. opening order to control exF. Tube below bulb approximately 90 cessive foaming, an mm. in length and extending at least 3 mm. below bottom of G all-gl aes stability G. Air inlet tube
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1
*3
RUBBER
TEST
STOPPER
TUBE
23mm x 140mm
It has proved particularly useful when the procedure requires the flask to be moved from one location to another, as, for example, when it is necessary to reflux a solution and then cool it in the sink before titration is carried out. It should prove useful also in any titration or reaction conducted under an inert atmosphere of carbon dioxide. The flask is easily constructed by sealing a test tube onto a flask fitted with an internal delivery tube. The size of the flaek and test tube depend on the work a t hand, Several flasks of this design have been in use in the authors' laboratory for over a year. Contrary to first opinion, they have been found easy to handle, very stable, and not subject to heavy breakage. Enough dry ice can be put in a 23 X 140 mm. test tube to last about 40 minutes. This includes a 15-minute reflux period during which the dry ice is in close proximity to a hot plate.
