Final answer:
The chemicals investigators spray to detect visible blood are Crystal violet, Cresol red, Thymol blue, Erythrosin B, 2,4-Dinitrophenol, Bromphenol blue, Methyl orange, Bromcresol green, Methyl red, Eriochrome* Black T, Bromcresol purple, and Alizarin. After staining, the blood smear is observed under a light microscope. Investigators can also evaluate the cellular components in blood by directly observing them with a microscope.
Step-by-step explanation:
The chemicals that investigators spray to detect visible blood are Crystal violet, Cresol red, Thymol blue, Erythrosin B, 2,4-Dinitrophenol, Bromphenol blue, Methyl orange, Bromcresol green, Methyl red, Eriochrome* Black T, Bromcresol purple, and Alizarin.
After staining, the blood smear is observed under a light microscope using the oil immersion objective lens. An initial scan to evaluate the appearance of the red blood cells and platelets is performed, followed by a more detailed analysis of the populations of white blood cells present.
Investigators can also evaluate the cellular components in blood by directly observing them with a microscope. A thin film of blood is created on a glass slide, and unstained and stained blood smears are used to observe individual cells.