Forensic drugs testing. Image 3 of 3. Results of drugs tests to provide evidence against suspected drugs dealers. Colours indicate the presence of a drug: blue (cocaine), black (cannabis) and orange (shaboo, an amphetamine). The cannabis test used cobalt thiocyanate solution. The cannabis sample was tested with Duquenois Reagent (containing vanillin). The amphetamine was tested with Marquis Reagent (sulphuric acid and formaldehyde). Cocaine is an alkaloid drug obtained from the coca plant (Erythroxylon coca). Cannabis is obtained from the cannabis plant (Cannabis sativa). Amphetamines are stimulant drugs. For a sequence showing the testing for these drugs, see images H200/196-198.