You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Napoleon

Context:
They maintained that the potassium tartrate used in his treatment prevented his stomach from expelling these compounds and that his thirst was a symptom of the poison. Their hypothesis was that the calomel given to Napoleon became an overdose, which killed him and left extensive tissue damage behind. According to a 2007 article, the type of arsenic found in Napoleon's hair shafts was mineral, the most toxic, and according to toxicologist Patrick Kintz, this supported the conclusion that he was murdered.

Question:
What do those who think Napoleon was poisoned cite as a symptom that would suggest this?

his thirst