Archived posting to the Leica Users Group, 2000/09/11

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Subject: RE: [Leica] Mercury (Hg) Batteries and Minamata
From: Paul Chefurka <>
Date: Mon, 11 Sep 2000 14:01:42 -0700


"The average mercury content of a standard 4-foot, 1.5 inch diameter, cool
white fluorescent lamp was reduced by 14% (48.2 mg/lamp to 41.6 mg/lamp),
and is expected to further decrease from 41.6 mg/lamp to 27.0 mg/lamp by


"Mercury batteries have a zinc anode, mercuric oxide cathode, and an
electrolyte of an aqueous solution of potassium hydroxide or sodium
hydroxide. The cell has a solid cathode of mercuric oxide and contains 20 to
50 percent mercury or mercuric oxide, by weight."

I can't find a number for the weight of a PX625, so I'd guesstimate at
around 1 gram.  That means it contains 200mg to 500mg of Hg, or roughly as
much as 10 standard fluorescent tubes.

But from

" Industry estimates show that between 450 and 500 million fluorescent lamps
are disposed of in the United States each year, dumping over 30,000 metric
tons of mercury contaminated waste into the nation's landfills"


>-----Original Message-----
>From: John Coan []
>Sent: Monday, September 11, 2000 4:16 PM
>Subject: Re: [Leica] Mercury (Hg) Batteries and Minamata
>Do you happen to know what mercury compound is in fluorescent tubes?  I
>wonder how much is in one industrial size light, vs. one PX-625? 
>Anybody else?