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A Few Significant Facts to be Kept in Mind in
Considering the Poesible Effects of Radium and
Nesothorium on the Human Organism.
1. Mesothorius decays 250 times as rapid as radium and conse-
quently in its pure state, weight for weight, its activity would
greatly exceed that of radium. However, the quantity of meso-
thorium is not expressed in milligrams by weight, but it is
rated in terms of radium, thus the activity of two compounds
compared bear the same ratio as the values assi ned to the
preparations.
2. Although meso horium itself is rayless, its first product,
which is rapidly formed after mesothorium has been separated,
gives powerful beta and gamna radiations. Consequently, in the
commercial production of mesothorium the operator must protect
himself against these penetrating radiations This is not so
necessayin the commercial production of radium as the product
giving rise to the penetrating gamn radiation (Ra C) ia formed
rather slowly.
3. The half value period of radium is 1580 yenra while that
of mesothorium is 6.7 years. This is of impotance in consider-
ing the accumulative effects of naterial that may be deposited
in the system.
4. In the decay of radium we have as the first product the
emanation with a half period of 3.8 dyas, followed by the active
deposit of rapid change (RaA, RaB, RaC), and then the active
deposit of slow change (RaD, Raz, RaF). Radium D and E enit
aoft beta cays and have half periods of 16.5 years and 4.85 dygs
respectively. Radiun P or Polonium enits alpha rays and has
a half period of 136.5 days. In the case of mesothorium the
emanation has a half period of 54.5 seconds, which is followed
Th A, B, & C, comparable to the active deposit of rapid change
in the radium series. ThC is followed by Thorium D (Th lead)
which is stable
It is important to note, that while there is generated from
Radon a product of comparatively long life emitting alpha rad-
iatuon there is no similar product generated in the thorium
series.
5. The maximum range of an alpha particle from the thorium
series is 8.6 cm, while from the radium series it is 6.94 em.
H. H. Barker.
Physical Laboratory,
January 25, 1926
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"ocrText": "A Few Significant Facts to be Kept in Mind in\nConsidering the Poesible Effects of Radium and\nNesothorium on the Human Organism.\n1. Mesothorius decays 250 times as rapid as radium and conse-\nquently in its pure state, weight for weight, its activity would\ngreatly exceed that of radium. However, the quantity of meso-\nthorium is not expressed in milligrams by weight, but it is\nrated in terms of radium, thus the activity of two compounds\ncompared bear the same ratio as the values assi ned to the\npreparations.\n2. Although meso horium itself is rayless, its first product,\nwhich is rapidly formed after mesothorium has been separated,\ngives powerful beta and gamna radiations. Consequently, in the\ncommercial production of mesothorium the operator must protect\nhimself against these penetrating radiations This is not so\nnecessayin the commercial production of radium as the product\ngiving rise to the penetrating gamn radiation (Ra C) ia formed\nrather slowly.\n3. The half value period of radium is 1580 yenra while that\nof mesothorium is 6.7 years. This is of impotance in consider-\ning the accumulative effects of naterial that may be deposited\nin the system.\n4. In the decay of radium we have as the first product the\nemanation with a half period of 3.8 dyas, followed by the active\ndeposit of rapid change (RaA, RaB, RaC), and then the active\ndeposit of slow change (RaD, Raz, RaF). Radium D and E enit\naoft beta cays and have half periods of 16.5 years and 4.85 dygs\nrespectively. Radiun P or Polonium enits alpha rays and has\na half period of 136.5 days. In the case of mesothorium the\nemanation has a half period of 54.5 seconds, which is followed\nTh A, B, & C, comparable to the active deposit of rapid change\nin the radium series. ThC is followed by Thorium D (Th lead)\nwhich is stable\nIt is important to note, that while there is generated from\nRadon a product of comparatively long life emitting alpha rad-\niatuon there is no similar product generated in the thorium\nseries.\n5. The maximum range of an alpha particle from the thorium\nseries is 8.6 cm, while from the radium series it is 6.94 em.\nH. H. Barker.\nPhysical Laboratory,\nJanuary 25, 1926"
}