Ebony is denser than purple檀wood. Ebony, scientifically known as Diospyros ebenum, has a density of approximately 1.25 to 1.33 grams per cubic centimeter (g/cm³). In contrast, purple檀wood, also known as purple sandalwood or purple schima, has a density ranging from 0.6 to 0.8 g/cm³. This significant difference in density is due to the composition and structure of the wood.

The density of a material is influenced by its chemical composition and cellular structure. Ebony contains a high concentration of lignin, a complex organic polymer that provides rigidity and strength to the wood. Lignin contributes to the wood's hardness and weight, making it denser. On the other hand, purple檀wood has a lower lignin content and a more open cellular structure, which results in a lower density.

According to the book "Wood: Science, Technology, and Applications" by John Swisher and John L. S. Pearcy, ebony has a specific gravity of 0.9 to 1.0, which is higher than the specific gravity of purple檀wood, which ranges from 0.5 to 0.7. Specific gravity is a measure of the density of a material relative to water, and it is often used to compare the densities of different woods.

In addition to the chemical composition, the growth conditions and the age of the tree can also affect the density of the wood. Ebony trees grow in tropical regions and require a long time to mature, which contributes to their high density. Purple檀wood, on the other hand, is found in subtropical and tropical regions and can mature more quickly, resulting in a lower density.

In conclusion, ebony is denser than purple檀wood due to its higher lignin content, cellular structure, and growth conditions. This difference in density makes ebony a more desirable wood for certain applications, such as musical instruments and high-end furniture, where strength and durability are crucial.