Ask Uncle Pai — Why do dogs eat grass?

Fomentation improves the circulation of the blood in the area. It takes away the waste products though the veins in the area.

Why do patients suffering from kidney stones avoid eating tomatoes and even leafy vegetables?

— Jofi Joseph, Nasik

There are various kinds of stones. Calcium oxalates also form kidney stones. Tomatoes and even leafy vegetables have calcium which can result in calcium oxalate.

How do we test gold? Is there any instrument that one can carry while buying gold?

— Anil Parikh, Ghatkopar (east)

If you go to any shop selling gold jewellery, you will find that the shopkeeper has a compact, dark-coloured siliceous stone. The gold to be tested is rubbed on this stone and from the colour and shade of the golden yellow mark on the touchstone, a good goldsmith can make out how pure the gold is.

What are moles? Why do they appear?

— Arun Nair, Dst Chandrapur

The complexion of human beings and animals is due to a layer of pigment in the skin called melanin. Moles appear on the body because of the accumulation of melanin at certain points in the skin.

Why does a dog eat grass sometimes?

— Rajesh Shanbhag, Mumbai

Dogs eat grass when they feel something is wrong with them. After eating grass, whatever is eaten and has remained in the abdomen is thrown out. They feel better after this.