The Philosophical magazine; a journal of theoretical, experimental and applied physics . s. Soc. London, vol. vi. p. 292) gives thevalue of a normal Daniell set up with solutions of the samemolecular strength, preferably of strength rn M SO4 100 OHo,where m is near 2—that is with copper sulphate nearly satu-rated, and zinc sulphate of equivalent molecular strength, andpure amalgamated zinc plates and electro-deposited copper—as M14 unit, or 1-099 true volt. None of these are very far from the value assigned to thestandard cell described above, viz. 1-102 volt, with equidensesolutions and
The Philosophical magazine; a journal of theoretical, experimental and applied physics . s. Soc. London, vol. vi. p. 292) gives thevalue of a normal Daniell set up with solutions of the samemolecular strength, preferably of strength rn M SO4 100 OHo,where m is near 2—that is with copper sulphate nearly satu-rated, and zinc sulphate of equivalent molecular strength, andpure amalgamated zinc plates and electro-deposited copper—as M14 unit, or 1-099 true volt. None of these are very far from the value assigned to thestandard cell described above, viz. 1-102 volt, with equidensesolutions and metals as described. [ 141 ] f>p\ ^ tm^) XVT. On Molecular Shadoivs in Incandescence Lamps. ByJ. A. Fleming, , {Lond.), Fellow of St. JohnsCollege, Cambridge, Professor of Electrical Technology inUniversity College, London*^. SINCE presenting a short note on the above subject in 1883many further opportunities have occurred for observingthe conditions under which molecular shadows are formed inincandescence carbon-filament lamps, and of correcting one or COPPERDEPOSIT. LINE OF\V DEPOSIT two statements then made. It has been observed in an immensenumber of cases, that not only do incandescence lamps becomecoated on the interior of the glass with a deposit of carbon,but that the envelope may have deposited upon it a metallicfilm, derived from the leading-in wires to which the carbonfilament is clamped. In the Edison lamp the platinum wireonly just passes through the glass, and is connected withcopper wires broadened out into a clamp ; the filament isgripped in these clamps and then electro-plated over withcopper to efix>ct a good junction. In the Swan lamp theplatinum wires are joined directly on to the carbon. It occa-sionally happens that there is an unusual amount of resis-tance at the clamps, or that by excessive electromotive forcemore current is forced through the lamp and more heat gene- * Coiiinumicatetl by tlic Physical Society: read Jiiiu- -27, 18s6.
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