T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERIiVG CHEMISTRY
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created b y t h e outrushing air which dragged microorganisms f r o m t h e surrounding air onto t h e plate. In order t o eliminate this undesirable effect we tried fastening funnels of various sizes b y means of a rubber attachment t o the cock. We found t h a t a funnel whose circumference was exactly t h a t of our dish gave us t h e best results so this method has been adopted for taking air samples rapidly throughout the plant. LABORATORY OF THE W&l. J. LEMP BREWINGCOMPANY ST. LOUIS .
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AN ETHER RECOVERY TUBE By J. M. PICKEL Received December 19, 1914
I n fat extractions with the Knorr flask, i t is.custom a r y t o recover the ether b y removing the extraction t u b e and putting in its place a test tube. The accompanying sketch shows an arrangement hy which this exchange of tubes and a t t e n d a n t loss of time and ether are obviated. During t h e extraction t h e ether drops from the point C into t h e funnel d , which conveys i t into t h e extraction t u b e B. When the extraction is finished, t h e other side of the tube A is brought under t h e point C ; this is E accomplished without interrupting the distillation, by merely turning t h e Knorr flask. The funnel, which A is made of either glass or metal, has the peculiarity of being a half funnel, covering b u t one-half t h e m o i t h of the t u b e A t o which i t is fused a t its lower end only. The extraction tube B need not /e be over 4 or j cm. long t o accommodate a n ordinary charge ( 2 g. subB stance) and instead of two holes near its top for the circulation of vapor, two V-shaped notches filed in its edge are equally efficient. The inside diameter of the standard /&e cylinder E is about 3.2 cm. ( 1 . 2 5 inches); t h e outside diameter of -4 should therefore he not less than 2 . 7 cm. ( 1 ~ / 8 inches). The length of A should be t h e greatest possible without touching t h e point C when i t is revolved. The inside diameter of the necks of t h e Knorr flasks need not, a n d should not, be less t h a n 2 2 or 2 3 m m . I n t h a t case, the extraction tube can be dispensed with, and in its stead a standard paper thimble, 1 9 m m . diameter, used. The thimble is placed inside the neck of t h e Knorr, its lower end reaching down t o within I cm. of t h e surface of the ether; i t m a y be conveniently supported in t h a t position b y a small copper wire permanently wound around i t , ends of t h e wire on opposite sides resting on top of t h e neck of the Knorr. T h e space gained in the cylinder E b y t h u s sinking t h e extraction thimble into the Knorr, makes i t possible t o give added length and capacity t o the recovery t u b e A . Moreover, the extraction takes place in ether
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vapor, a t practically t h e boiling point of ether, and i t is claimed t h a t an extraction in t h a t case is complete in about 4 hours instead of t h e usual sixteen. NORTH CAROLINA DEPARTMENT OF AGRICULTURE RALEIGH
______ A CONVENIENT FORM OF WEIGHING PIPETTE By A. T. MERTES Received January 27, 1915
For conveniently and accurately weighing o u t quantities of glycerine such as are used in the determination of glycerol b y the acetine method, the writer devised t h e form of apparatus shown. It is convenient a n d useful for weighing out oils for t h e determination of t h e Iodine Number. especially those oils having a high iodine absorption, and which require an accurate weight. For Koettstorfer and Reichert-Meissl Numbers, the pipette may be calibrated so as t o assist in delivery of t h e proper amount of fat or oil. The pipette can be made b y a n y one having a little skill in glass working. The writer uses a n old I O cc. pipette and fuses a glass stopcock t o one end. T h e other end of t h e bulb is draivn out and bent into a hook as shown in t h e sketch. I n order t o fill the pipette, a rubber t u b e is attached t o t h e upper end and t h e desired amount of t h e fat or other substance sucked up into i t . The stopcock is then closed, t h e delivery t u b e wiped off and the pipette suspended b y t h e hook from a balance and weighed. 6537 WOODLAWK AVEXUE,CHICAGO
A FILTER-PIPETTE FOR ETHER B y J. 34. PICKEL
Received December 17, 1914
The accompanying illustration shows a device for filtering ether without waste and simultaneously de-
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livering it in requisite measure into fat extraction flasks.
