Editing Forensic science (section)

===Toxicology===
A method for detecting arsenious oxide, simple [[arsenic]], in corpses was devised in 1773 by the Swedish chemist, [[Carl Wilhelm Scheele]].<ref name=DPaC>{{cite book|last=Bell|first=Suzanne|title=Drugs, Poisons, and Chemistry|publisher=Facts on File|location=New York|isbn=978-0816055104|page=8|url=https://books.google.com/books?id=lq8IvpohnCwC&pg=PA8|url-status=live|archive-url=https://web.archive.org/web/20160427082830/https://books.google.com/books?id=lq8IvpohnCwC&pg=PA8&dq|archive-date=27 April 2016|date=October 2008}}</ref> His work was expanded upon, in 1806, by German chemist Valentin Ross, who learned to detect the poison in the walls of a victim's stomach.<ref>{{Cite book|title=Forensic Analysis and DNA in Criminal Investigations: Including Cold Cases Solved|last=Parker|first=RJ|publisher=RJ Parker Publishing|year=2015|isbn=978-1514348369|pages=66}}</ref> Toxicology, a subfield of forensic chemistry, focuses on detecting and identifying drugs, poisons, and other toxic substances in biological samples. Forensic toxicologists work on cases involving drug overdoses, poisoning, and substance abuse. Their work is critical in determining whether harmful substances play a role in a person’s death or impairment. [https://www.dseodisha.com/forensic-science-exploring-key-types/ read more]

[[Image:Marsh test apparatus.jpg|thumb|left|Apparatus for the arsenic test, devised by [[James Marsh (chemist)|James Marsh]]]]
[[James Marsh (chemist)|James Marsh]] was the first to apply this new science to the art of forensics. He was called by the prosecution in a murder trial to give evidence as a chemist in 1832. The defendant, John Bodle, was accused of poisoning his grandfather with arsenic-laced coffee. Marsh performed the standard test by mixing a suspected sample with [[hydrogen sulfide]] and [[hydrochloric acid]]. While he was able to detect arsenic as yellow [[arsenic trisulfide]], when it was shown to the jury it had deteriorated, allowing the suspect to be acquitted due to reasonable doubt.<ref>{{cite web |url=https://www.nlm.nih.gov/visibleproofs/galleries/technologies/marsh.html |title=Visible Proofs: Forensic Views of the Body: Galleries: Technologies: The Marsh test |access-date=2015-11-04 |url-status=live |archive-url=https://web.archive.org/web/20151007131101/https://www.nlm.nih.gov/visibleproofs/galleries/technologies/marsh.html |archive-date=7 October 2015 }}</ref>

Annoyed by that, Marsh developed a much better test. He combined a sample containing arsenic with [[sulfuric acid]] and arsenic-free [[zinc]], resulting in [[arsine]] gas. The gas was ignited, and it decomposed to pure metallic arsenic, which, when passed to a cold surface, would appear as a silvery-black deposit.<ref>{{cite book|last=McMuigan|first=Hugh|title=An Introduction to Chemical Pharmacology|publisher=P. Blakiston's Son & Co.|year=1921|location=Philadelphia|pages=396–397|url=https://books.google.com/books?id=n4I6AAAAMAAJ|access-date=2007-12-16}}</ref> So sensitive was the test, known formally as the [[Marsh test]], that it could detect as little as one-fiftieth of a milligram of arsenic. He first described this test in ''The Edinburgh Philosophical Journal'' in 1836.<ref>{{cite journal|title=Account of a method of separating small quantities of arsenic from substances with which it may be mixed|journal=Edinburgh New Philosophical Journal|volume=21|year=1836|pages=229–236|author=James Marsh|url=https://books.google.com/books?id=FR4AAAAAMAAJ&pg=PA229|publisher=A. and C. Black|url-status=live|archive-url=https://web.archive.org/web/20150904044244/https://books.google.com/books?id=FR4AAAAAMAAJ&pg=PA229#v=onepage&q=%22detecting%20the%20presence%22&f=false|archive-date=4 September 2015}}</ref>