The dosimeter, developed by George V. Taplin,
Clayton Douglas, and B. Sanchezet, was
described in “A Sensitive Colorimetric Method for Radiation Dosimetry”
(UCLA-118). The solution consists of alcohol-free chloroform and the dye
brome-creosol purple. When the chloroform absorbs radiation energy,
hydrochloric acid is produced which changes the dye color from purple to
yellow. Sodium hydroxide is added to adjust the sensitivity.
The February 28, 1950 issue of the Los Angeles Times reported:
"Designed specifically to measure large doses of gamma and X rays scattered by an atomic explosion, a new radiation indicator has been perfected by UCLA researchers, it was announced yesterday."
The following quotes from 1952 (Humboldt Standard, June 26, 1952) clearly
refer to this dosimeter even though some of the details are a little
"A small metal box known as a colorimetric
dosimeter that can determine your chance of life or death in an atomic
attack, is being developed by the University of California at Los Angeles,
it was revealed here."
"The two-inch black box is a chemical radiation
detector and contains three tubes [rather than the six in this device] of
purple liquid. Each tube is set to absorb a certain amount of radiation
"After that point if one tube turns yellow - -
you'll survive if given blood plasma and treatment. If two tubes turn yellow
- - there's a slightly less than 50 percent chance you'll survive. If all
three tubes turn yellow - - 99 chances out of 100 you'll be dead within six
"Development of the device is being supervised by
Dr. Stafford Warren, Dean of the UCLA Medical School and California's
official radiological expert."
"State civil defense officials said every
Californian may someday wear one around his neck like an army dog-tag."
"Each box would be riveted shut to prevent trading or
purchasing of dosimeters. Name, address and blood type would be stamped into
"The box would be opened only at a casualty
station after an atomic bombing and medical corpsmen would be able to
determine immediately to what degree the person had been exposed to
radioactivity and the chances for saving the victim."
"Dr. Warren said before the boxes become
acceptable for public use the federal bureau of standards must give them
approval and the $2.50 per unit cost must be brought down to 25 or 50
"The purple liquid contained in the box is
potassium hydroxide, chloroform and a special litmus-type dye. The tubes are
made of a special pyrex to prevent radiation from minerals in the glass
"When enough injurious gamma rays penetrate the
liquid, part of the potassium compound changes structure. It combines with
the chloroform to produce hydrochloric acid which turns the dye from purple
Size: 1 5/8” x 2.5” x
K.Z. Morgan, unpublished manuscript, prepublication
copy of "Health Control and Nuclear Research" 1952.
Wane Sargent. Colorimetric Dosimeter Will be Used to
Determine Radiation. Humboldt Standard, June 26, 1952.