The acid phosphate test is among the most common and is even available via home testing kits, which can be purchased online. The acid phosphate test detects a protein in semen known as acid phosphatise. The test is referred to as a presumptive test because these tests make use of a certain chemical to establish the presence of a certain body fluid or chemical. In forensic science, presumptive tests can do two things: they either exclude a substance from being semen or confirm with a good probability that the substance is semen. The acid phosphate test hydrolyzes the protein in the semen sample; consequently, if semen is actually present, a color change will be noted in the intensely colored azo dyestuff. Presumptive tests have the chance of false positive results, which can indeed be misleading. Further confirmatory testing is required following the results of a presumptive test that gives a positive result.