Re:influence machine

[inet@intellisys.net (brian whatcott)]

At 03:57 PM 4/8/97, SCIAMANDA@edinboro.edu wrote:
> Ludwig wrote:
> ... The radioactivity collected was 
> shown to decay (to background level) in three hours. The paper was published 
> in 1902; Rutherford was at McGill University at that time. . . .
> ....

> kowalskiL@alpha.montclair.edu 


> It is curious that the time of decay "to background level" is reported, 
> rather than a half life.  Were the statistics of radioactive decay not yet 
> understood - when (and by whom) was this subject first understood?
> Anyone know?
>
> Bob Sciamanda   

Becquerel discovered radioactivity in 1896 using a fluorescent uranium 
potassium sulphate card which affected a covered photographic plate.

Schmidt showed thorium behaved similarly.

Marie Curie showed pitchblende was more active than uranium.
With her partner, she discovered polonium and radium by concentrating  such 
compounds. (1898)

Debierne discovered actinium later.

By 1902, Rutherford and Soddy published a law of radioactive change 
for thorium which proved to have general effect.
 Half-life was a more popular formalism than exponential decay rate, initially.

( I used a British text which in their usual style provides an historical 
context for discoveries - a feature which seems not to have much appeal to 
the US textbook purchaser)
Ref:  Physics, Starling & Woodall, Longmans.

Regards
brian whatcott <inet@intellisys.net>
Altus OK