The procedure we used to make soap was developed in the early 1800s. back then, most soap was very harsh on the skin, why do you think this was? what technology has significantly improved since then in order to minimize this harshness?

The soaps were made with sodium or potassium hydroxide salts its pH is greater than the neutral, i.e basic and quite caustic.

Today, the technique called the saponification has been developed

Explanation:

In the early stages, for many years soap was made from animal fat and lye.

The soaps were made with sodium or potassium hydroxide salts its pH is greater than the neutral, i.e basic and quite caustic.

Surfactants especially anionic surfactants are commonly used due to their ability to solubilise fats. But extensive use of anionic surfactants like sulfonates can damage our skin by disrupting lipid membranes which protects our skin.

Also, during those days the concept of stoichiometry of a reaction was not that much involved in the making of soaps.

Therefore, too much lye was used, which make the soap too alkaline , which causes irrtiation in skin.

Today, the technique called the saponification has been developed.

Thus, exact amount of lye and fat required for the complete saponification reaction from the saponification value of a soap can be determined. Which reduced the harshness.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).