Which substance is used only as a filler in autopsy chemical mixtures?

Perlite is a naturally occurring volcanic glass that has been processed to create a lightweight, porous material. In the context of autopsy chemical mixtures, it is primarily utilized as a filler due to its properties that allow it to absorb excess moisture and provide bulk without reacting with the other chemicals. This makes it suitable for use in mixtures where a non-reactive, inert filler is needed to maintain the desired consistency and performance of the overall formulation.

On the other hand, silica is often used for its desiccant properties, calcium carbonate functions in various chemical reactions, and glycerin serves as a lubricant or humectant. Each of these substances has distinct roles beyond that of merely being a filler, which reinforces the unique contribution of perlite in this context.