Emilio Segrè Visual Archives

More than 30,000 photos of scientists and their work

Attention ESVA Patrons:

The Emilio Segrè Visual Archives’ site is moving soon and adopting an open access approach to digital image sharing. Once we have transitioned to the new site in 2021, we will no longer charge for our high-resolution digital images or usage fees (note that we do not hold copyright to all the images in our collections and you will still need to obtain permission for those which we do not own).

If you are working on a long-term project, we advise you to wait until the migration is complete so that you may obtain our copies for free. If you cannot wait, email us at nbl [at] aip.org and we will do what we can to assist you. We will not be offering refunds for past purchases.

For more information, please visit our FAQ page on the Ex Libris Universum blog. 

Cottrell Frederick F2

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Cottrell Frederick F2

Image title: 
Western Precipitation Experiment Station
Credit line: 
Western Precipitation Corporation, courtesy AIP Emilio Segrè Visual Archives, gift of Wayne Sproull

"Cottrell precipitators are widely used to collect flyash from coal-fired electric power plants, thus minimizing air pollution by such ash. However, in 1957, it appeared that oil-fired power plants might soon be required to follow the same practice. Therefore W. P. ordered me to set up an experimental precipitator at the El Segundo (oil-fired) Steam Station of Southern California Edison Co. to ascertain how a precipitator would perform there.
This photo shows the tests in progress in 1957. The center man in the group of three is Prof. A. J. Haagen-Smit of Cal Tech, who was in charge of a group measuring the concentration of SO2 [sulfur dioxide], SO3 [sulfur trioxide], and other gases in the stack gas stream during our tests. He was the first one to discover how Los Angeles smog, containing ozone, is generated by sunlight acting on hydrocarbons and oxides of nitrogen in the air."

Photo date: 
circa 1957
Original format: 
1 photographic print (black and white; 4 x 6.5 inches)
Cottrell, Frederick Gardner, 1877-1948
Haagen-Smit, A. J. (Arie Jan), 1900-1977