The castings are then inspected for radioactivity to find out any penetration of salts into cracks.
Absence of salt penetration indicates absence of cracks.
Sulphuric acid is then added to the aqueous solution to precipitate lead as lead sulphate.γ-rays emitted by the radio isotopes (Co) can be used in the treatment of cancer.
The basis of such a treatment is, that the radiation tend to destroy cancerous cells more easily than the normal cells.
In this technique, the sample containing very small amount of the stable isotope of the element to be investigated is bombarded with neutrons and the element of interest is converted (i.e., activated) into its radioactive isotope.
The radioactivity of this radioisotope is measured.
Thus, by determining the amounts of parent radioactive element and the isotope of lead in a sample of rock, the age of rock can be calculated.
This technique is gaining importance in analytical chemistry these days.
It can help in the detection of even one part of the element per billion parts of the sample.
Radio isotopes are frequently used as tracers or tagged atoms in may processes in different fields like surgery, medicine, agriculture, industry and chemistry.
In tracer techniques, a radioactive isotope is added to the reactants and its movement is studied by measuring radioactivity in different parts. For example, in order to find out if blood is circulating to a wound or not, a radioactive isotope is injected into the blood stream.