Arsenic belongs to semi-metals and has not only chemical and medical, but also historical value — with its help in the last centuries poisoned objectionable people. However this element has for the person and medicinal properties. What is arsenic — medicine or a poison? We will consider the answer to this question in this article.
is the important nutritious element necessary for normal activity of the person. Let's consider what role it plays in our life in what products contains and what the shortcoming and a surplus of this substance can turn back for health.