[NM020AAW], Technical Note, Thomas Alva Edison, July 1st, 1886


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[NM020AAW], Technical Note, Thomas Alva Edison, July 1st, 1886

Editor's Notes

"Patent acct Lamp Co-- Soak patent To effectually absorb all the water within the bulb of the lamp and to cause water to be formed so that it may be absorbed so as to get rid of the Oxygen is object of the patent. After the Lamp has had all the water taken from it by passing pure dry Hydrogen through it from a soure of Hydrogen & all the air driven out by displacement due to the inrush of the Hydrogen, a small pellet of a water absorbing substance such as phosphoric anhydride is put in the lamp and while it is full of Hydrogen put on the pump and exhausted, and Oxygen present combines with the Hydrogen by the action of the incandescent filament & forms water at a low incandescence & this is absorbed by the pellett of pece of phophoric anhydride, which remains in the lamp after it is sealed off and ready for market, it also absorbs any water as water that might have been in the globe; a piece of phosphorous may be used instead of the phosphoric anhydride & this is ignited while Oxygen is still in the globe & before the Hydrogen has been passed the phosphorous burns to phosphoric anhydride it should be put in a small recepticle so that in burning the white clould of phos anhydride will not rush upwards & coat the sides of the lamp-- Chloride of calcium & other absorbants may be used but phosphoric anhydride I think is prefereable. The pelet when put in the lamp must be made to fall to the bottom of the lamp where it will adhere and where it will remain during the use of the lamp, as even phosphoric anhydride gives off a slight amount water when strongly heated. Want a strong claim on this. Th use of dry Hydrogen in the lamp as the gas to start with to exhaust and a powerful water absorbant either in the pump or allowed to remain permanently in the Lamp is used, the latter preferable. Claim heating the filiment at first to lower incandescence than it is to be burned at to cause the Oxygen to combine with the Hydrogen to form water-- PS I forgot to mention that while the lamp is being exhausted the bulb is heated continuously by immersion in hot oil bath or from heat running from a chimney & flame. Thus-- [drawing with fig label "bunsen burner"] Make a claim for this also for it in combination with the [Pt?] in Lamp & the dryer in lamp or pump-- Edison"



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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University
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