Bulletin . na clay, 25; spar (BrandywineSummit), 20; flint (Ohio, 8 hr. grind), 20. The body was prepared in the usual manner according tofactory practice and the trials jiggered in the form of smallcrocks (Fig. i) which could be nested closely so that all pieceswould receive the same heat treatment. The trials were made in different thicknesses, varying mm. to 7 mm., by adjusting the jigger tool. The trials wereburned to cone 12^2 ^^d punctured under transformer oil (Fig. 2),the voltage being increased gradually by a rheostat. As soonas the trial was punctured, the current was immedia
Bulletin . na clay, 25; spar (BrandywineSummit), 20; flint (Ohio, 8 hr. grind), 20. The body was prepared in the usual manner according tofactory practice and the trials jiggered in the form of smallcrocks (Fig. i) which could be nested closely so that all pieceswould receive the same heat treatment. The trials were made in different thicknesses, varying mm. to 7 mm., by adjusting the jigger tool. The trials wereburned to cone 12^2 ^^d punctured under transformer oil (Fig. 2),the voltage being increased gradually by a rheostat. As soonas the trial was punctured, the current was immediately broken. The thickness at the point of puncture was measured bya micrometer. Five to ten trials made of the same thicknesswere punctured in each case. Whenever puncture took place 1 An abstract of work done in 1909-10 in partial fulfilment of requirements for M. in Ceramics at the University of Illinois, under supervision of R. T. Stull. 28 DIELECTRIC STRENGTH OF PORCELAINS. /=?ADCL/F^£:. /D£r^/L5 OF -TZl tH W/////////. fttr- 7ZA through a flaw, the trial was rejected. The voltages requiredfor puncturing sound trials of the same thickness were averaged,the thickness being plotted on the ordinate and voltage on theabscissa (Fig. 3). r/MM5 y^Af C£/fSOC i^a^ -r/K /^/ff3 /fADCU/^/^E y yy y ^ r--^ ^ 3 ^y y- / y /, y -^ r V) -^ yi ^/ Kl^ x/ ^ y -^ T-fWA/. By^Ll. C^-^ y /Vo. / y__ y £^ C/-t/r\/-^ C/-y^y ^S y A ^?^ i /Ol 000 1 _^2C x>oo 3C 000 -*; X}00 J5i3 000 60C ?>iX> 70c :ioci ao •ooo 90 006 7 /oao!. V Calculating the average puncture voltage per mm. thick-ness for all trials tested, assuming that the puncture voltageis directly proportional to the thickness, gives a voltage of 14, point is plotted and the hea^y dotted straight line passes DIELECTRIC STRENGTH OF PORCELAINS. 29 from the origin through it. Owing to the fact that a voltagehigher than 100,000 was not available, pieces over 6V2 thickness could not be tested.
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Keywords: ., bookcentury1900, bookdecade1900, bookpublisherurbana, bookyear190
