Poison

       Arsenic is a natural semi-metallic chemical that is found all over the world in groundwater. They can also be found in tocks, soil, air, plants and even animals. One of the main catches that makes it very dangerous is that it has no taste or even smell and it can even be found in its pure form in steel gray metal. Arsenic Poison can be caused by the ingestion, absorption, or inhalation. If it is not treated it can can cause many health complications, one of those being deathArsenic was used as a In some cancer treatment arsenic has been useful and in some  studies its shown to send the disease into remission and help to thin the blood. The treatment is actually still being test but they hope for it to be more promising in the future. One of the main causes of arsenic poisoning world wide is the groundwater that people are drinking. It contains high levels of toxins and the water becomes contaminated by the rocks that release arsenic. 

There are different types of symptoms just depending on the amount or way the arsenic is actually ingested. If the poison is ingested orally then within thirty minutes the first symptoms to appear are:
~drowsiness 
~headaches 
~confusion 
~terrible diarrhea 

Now is the arsenic is inhaled or a less concentrated amount has been ingested then the symptoms are most likely to be different and take longer to emerge. The patient that had taken the arsenic poison may start to suffer convulsion and their fingernail pigmentation may change also known as leakonychia. In more severe cases some of the cases could include:
~metallica taste in mouth
~mouth produces extra saliva
~problems swallowing
~blood in the urine 
~cramping muscles 
~loss of hair
~stomach cramps
~convulsion 
~excessive  sweating
~breath smells like garlic  
~diarrhea
~vomiting  

http://www.medicalnewstoday.com/articles/241860.php
http://io9.com/5942161/the-deadliest-poisons-in-history-and-why-people-stopped-using-them
http://listverse.com/2012/12/02/10-poisons-used-to-kill-people/