Thanks for using the science buddies forum! I think the first step for your son is to think through the scientific method and outline the process he wants to use to test his hypothesis. Then he can start to think through the smaller details, like where to acquire his materials.
I presume he wants to find out if a person can dissolve their kidney stones by orally ingesting corn silk tea. But this will be a complicated question to answer. You can’t just pour some tea over calcium (which is what most kidney stones are made of) and see what happens. This is because ingested corn silk tea will not pass directly through a person’s kidneys as part of its journey through the digestive track. Rather, the kidneys work by filtering our blood of salt, toxins, and water (you can read more about this process here: https://kidshealth.org/en/teens/kidneys.html
). However, if there is an element of corn silk tea that stays intact throughout the digestion process and ends up getting filtered directly through the kidneys, then you could set up an experiment where you apply this ingredient directly to a fake kidney stone to see if it dissolves. Your son will need to do some more research to decide if this is a realistic approach.
To answer your other questions:
1. There are four types of kidney stones. Most are made from some combination of calcium, uric acid, magnesium, ammonium, and phosphate. Rarely, kidney stones are made of cystine. You can see more detailed descriptions here: http://www.kidneyfund.org/kidney-diseas ... tones.html
2. It would be easiest to buy calcium powder (which you can do online or at a health store) but you could also find many of the other chemicals in powder form, as vitamins, and/or through scientific laboratory websites (such as Sigma-Aldrich).
3. As long as he is not working with any dangerous chemicals, he could do this experiment at home. However, he needs to make sure he has a clean, uncontaminated space to work and the proper materials (such as latex gloves) so he doesn’t accidentally mix chemicals or introduce contaminants into his experiment.
4. The best way for him to visualize the effect of the corn silk tea (or active ingredient) would be to take pictures of his “kidney stone” before, during, and after the corn silk tea is applied. For quantitative data, he could also measure the diameter of his kidney stone before starting and then re-measure it at regular time intervals after the corn silk tea is applied. Then he could create a graph of the diameter over time to show that the size of the kidney stone is shrinking.
I hope this helps him get started! Hopefully he can do some more research to explore the feasibility of this project before going further. And of course, let me know if you have any other questions!