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TlI!i J O i ~ K Y A I . 01: I.\~I>l~.S7'!?!.!Id AN AUTOMATIC PIPETTE. T. 0 . Sbnrx. Rrceiv-ed November 15, UY
1911.
Evcry chemist engaged either in routine work or in research involving a considerable number of determinations has learned t o appreciate the value of any automatic or labor-saving device he may finil available. The automatic pipette herc described is oflered because of its simplicity, accuracy, ready adaptability to any voluinc requirecl, and especially, bccause it is casily set up from materials m i l apparatus found in every laboratory.
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ipoint apparatus mare accurate and more easily controllcil than those ordinarily used. IVith all common types, the chicf difficulty is in obtaining a uniiorn? rise in temperature, and in duplicating the conditions a t another time. The following simple picce of a1)paratus needs little explanation b e p n d the illustration. I t is based upon the Thielc tubc, with elcctricity supplanting the Bunsen flame. as heating agent. The lowcr half of the side arm is wound with rcsistancc wire, such as iinc manganin or nichriirnc. The v h ~ d o arm is then enclosed with asbestos paste as s h o i n in thc cut. Using a lamp hoard, or rh s m t through the heating coil may be varied a t will, and thus the rise oi temperature vcry accurately controlled. Iiy calibrating the instrument i n t e r m s of lamps a n d temperature it is only necessary to turn on t,hc prnpcr number of lamps and the rise ( o i tenipcra-
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The only materials needed are: A - -A bottie of a sizc adapted to the reagent which it is t o contain. B--A three-way stopcock burette. C----A fine capillary tube long enough to reach from the zero reading on the burette t o the top of the solution in the container. D-Giass and rubber tubing to set up as shown in the illustration. By raising or inwering the capiliary tube C, the pipette may be adjusted to deliver any exact quantity within the limits of the capacity of the burette used. I t is obvious t h a t if the capillary tube is drawn out as fine as possible and the burette and container brought near the same level. the accuracy of the pipette is practically t h a t of the burette. NBIVH ~ a ~ s a m ADKICULWRAL s E x ~ f m ~ aSTATION. m DUR"*>,.
A NEW MELTING-POINT APPARATUS. B Y D. S. P n ~ n . Received October 26. 1911.
In the course of some research work with organic compounds, i t became necessary to have a melting-
ture will be exactly uniiorm each time it is used. 'I'he ratc of change may be varied from an almost iniperceptible rise, t o a very l-a1)id'one, and the range is limited only by the Auid used. In making a series oi dctcrminations it is v convenient t o turn ofl, say, nnc lamp, while prcqiai-in~ the tubes, thus rctaining the temperature within a few degrces of the mclting point and saving much time usi~allyspent in needlcss delay For suhstanccs whose melting points vary with the rate a t which they are heated, this devicc is especially convenient. I t has been in usc for over a year in the organic research laboratories of Cornel1 University, has given complete satisfaction and has supi>lanted the oldw types. C0nh-Bi.L ONIVIRSITY,
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