V O L U M E 2 8 , N O . 11, N O V E M B E R 1 9 5 6 Autoflller W. 0. Phillips, Technical Division, Goodyear Atomic Corp., Portsmouth, Ohio
laboratory operations frequently require withdranlng R small volumes of previously prepared solutions from large storage containers. T o facilitate this operation, an automatic OUTIXE
filler utilizing the siphon principle has been designed and fabricated a t the Goodyear Atomic Corp. laboratories. This filler, with the exception of the ground-glass joint and center filler-tube, C, is constructed of heavy-walled tubing to minimize breakage. Filler-tube C and tube D should extend approximately 1 inch beyond the lower end of the ground-glass joint. The delivery tube from the storage container is attached to arm A on the filler by plastic tubing. A similar piece of tubing must be attached to arm B and extended above the liquid level of the storage container (a ball check valve in arm B may be substituted for the tubing). The filler is placed in a withdrawal bottle fitted with a ground-glass joint. The stopcock is opened and the siphoning action started by means of a rubber squeeze bulb attached to the storage container. The liquid level in the withdrawal container will cease to rise \Then the solution reaches annulus D. However, the solution will continue t o rise in arm B until it attains the level of the solution in the storage container (or until the ball check valve is closed). T o change withdrawal bottles, it is necessary only t o close the stopcock, slowly lift th(a filler, and allow the solution contained in arm B to drain into the bottle, then insert the filler into an empty withdrawal bottle. (Sufficient room will remain in the bottle for the solution contained in arm B , if tubes C and D extend 1 inch beyond the ground-glass joint.) The ground-glass joint may be of the outer type, which would minimize the danger of pouring the solution over a greased surface. Work performed under Contract-.iT-(33-2)-1, U. S. Atomic Energy Commission.
1801
by Mitzner, B. M.,AppLSpectroscopy 10, 75 (KO.2, 1856)],and providing for the storage of predetermined amounts of potassium bromide in individual containers in order to guarantee its puiity. Gelatin capsules of various volumes are readily obtainable, and a size can be chosen that will be appropriate for the particular type of potassium bromide die employed. I n practice, 200-mesh potassium bromide (obtainable from the Harshaiv Chemical Co.) is carefully dried a t 150" C. (vacuum drying is recommended). The longer portion of the gelatin capsule is filled with the dried potassium bromide, and is occasionally gently tapped in order to ensure an even distribution of the material. Any excess is wiped off and the gelatin cover is put on. The filling procedure should be carried out in a "dry box,' ' or in an air-conditioned room on a dry day.
A large number of capsules can be filled a t one sitting, to supply the needs of the infrared spectroscopist for several months. T h e filled capsules should be placed in an airtight jar or desiccator for future use. When needed, the capsule is opened and its dry contents are emptied into a miying device along nith the sample under investigation. T h e volume of the gelatin capsules is very constant. If the capsule is carefully filled, amounts of potassium bromide are reproducible within 2%, which is satisfactory for most quanritative and qualitative infrared procedures. Where great precision is required, the potassium bromide qhould be weighed, as the time of tapping during filling can make a difference in the weight of the reagent. This difficulty can be overcome by neighing the empty capsule and aftern-ards the hlled capsule, thus establishing the true weight of the potassium bromide. (The potassium bromide is not exposed to atmospheric contamination during weighing.) T h e procedure described enables the analyst to have known amounts of potassium bromide readily available and in a very pure state. Because of the low water content ensured by this technique, highly transparent potassium bromide pellets are obtainable. A further application of this procedure is for micro samples. I n order to prevent loss of small quantitieb of sample, they may be added directly to potassium bromide contained in an oversized capsule and the two components mixed in the capsule n i t h the aid of a mechanical vibrator. The contents ran then be emptied directly into the potassium biomide die with a minimum loss of material.
Gelatin Capsules for Potassium Bromide Infrared Tee hnique Bernard M. Mitzner, Chemical Warfare laboratories, Army Chemical Center, Md. HE
Determination of Ozone by Thermal Conductivity Williom J. Burlant and William A. Cannon, Chemistry Department, Scientific laboratory, Ford Motor Co., Dearborn, Mich.
potassium bromide pressed pellet technique has become
Tvery useful in infrared spectroscopy, as it avoids many difficulties usually encountered in handling solid samples by other standard procedures [Stimson, M. M., J . A m . Chem. SOC.74, 1805 (1952)l. T h e amount of sample and potassium bromide that is employed depends upon the type and size of die available and may be measured by either weighing or approximating the amount by eye. T h e weighing technique has merit in precise quantitative techniques; however, it is very time-consuming and the potassium bromide both on the sample pan of the balance and in the reagent bottle absorbs moisture during the process. (The potassium bromide in the reagent bottle is lumpy after exposiire to the atmosphere, and has an excessively strong 3-micron nater absorption band.) The approximation method is of value only in rough qualitative determinations. A technique which is efficient and virtually eliminates moisture contamination is based upon measuring the potassium bromide as :i funrtion of volume rather than weight [described in detail
laboratory, there was a need for rapidly detecting small IAlthough changes in the ozone concentration of an oxygen stream. an electrometric (3) and several spectrophotometric i i THIS
( 2 , d ) methods are described, there seem t o be no published data on the use of thermal conductivity differences for the determination. Inasmuch as this approach seemed most convenient, its applicability was investigated. T h e preliminary data are presented in this communication, for this aspect of the problem has been discontinued. The difference in thermal conductivity between the reference gas (oxygen) and ozonized oxygen of knovin composition was used to prepare a calibration curve (millivolts us. ozone concentration). T h e important considerations in obtaining reproducible data are maintaining (1) a constant gas flow through the arms, for a 5070 increase in the flow rate caused an SyGerror in the concentration determination, and (2) a draft-free and temperature-constant environment. When the cell was sheathed
