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’ RAIL JOINTS AND BONDS 561
Kind of Ware. No. of Trials. A^^^0 Condition.
Ohio Pottery Company S .. 2 .. 1.5 . .Uniform and smootheffect on glaze.
Royal Berlin ............... 2 .. 1.8 . .Uniform and smootheffect on glaze.
FOURTH : Effect of Ferric Oxide Ignition on Glaze.
Kind of Ware. No. of Trials.^^^^ Condition.
Ohio Pottery Co. S .... 2 .. .001 .. Glaze practically unaffect-ed. No crucibles cracked.
Royal Berlin ............ 2 .. .006 .. Glaze very badly discol-ored. One crucible cracked.
FIFTH : Casseroles and evaporating dishes were run through limestoneanalysis and showed an average loss in weight of .O’Ol per cent withglaze left smooth and-clean.SIXTH : Casseroles’ and evaporating dishes were run through iron and
steel analysis and showed an average gain in weight of .002 per cent withglaze left smooth and clean.SEVENTH: ’Photo micrographs were taken of different glazes and
showed a practically homogeneous’ body free from pits and bubbles.EIGHTH : Fractures were made and examined microscopically and
showed perfectly vitreous, free from any granular structure.
AN EXPERIMENT IN LIGHT.Look at an open arc light through the stretched silk of an open umbrella,
and a clear) and distinct spectrum will be seen. For laboratory purposes,an ordinary silk handkerchief, tightly stretched,, may be used for the samepurpose. , /
RAIL JOINTS AND BONDS.Modern Practice in the Construction and Maintenance of Rail Joints
and Bond^, in Electric Railways is the title of Technologic Paper, No. 62,just issued by the Bureau of Standards, Department of Commerce. Thepaper is largely a compilation of information in the nature of data aridopinions submitted by forty-two electric railway companies who answeredinquiries sent out by the Bureau.Analysis of the data shows that soldered bonds have been demonstrated
to be unsuccessful and are now practically obsolete, while all other typesof standard bonds are capable of giving good results, but only when care-fully installed.Loose rail joints are shown to be the most prevalent cause of bond fail-
ures and as a result there appears to be a marked tendency toward theadoption of improved methods’ and materials in their construction. Theadoption of various types of welded joints to take the place of the commonbolted joint appears to be in progress in most of the larger cities. Thewhole problem of track bonding is shown to be in a state of evolution,owing to new inventions and recent improvements in methods of con-struction, and, as a result, complete standardization of these practices can-not be expected for some time to come.The character of track bonding is determined largely by the necessity
for good operation and the prevention of stray currents which have a" cor-rosive action on underground pipes. Economic considerations are shownto be of secondary importance.
Copies o’f the publication will be sent free to those interested who ap-ply to the Bureau of Standards, Washington, D. C.