Bile salts give stool its characteristic brown color. If there is decreased bile flow caused by a condition affecting your gallbladder, liver, or pancreas (such as cholecystitis, gallstones, giardia, hepatitis, chronic pancreatitis, or cirrhosis), there may be a lack of bile in stool, making them pale or clay colored.
The writer uses irony in the passage with the sense of purposes to it. This purposes includes, criticizing the adults, to sympathize the children and also to create a tragic situation in the passage. Firstly, the writer uses the technique irony to criticize the adult.
Before looking for the examples for verbal irony, it is advisable that you understand the concept of irony in general. In simple words, it can be a situation or a conversation, where the first part is contradicting the second part or indicating something which is opposite to the literal meaning.