The nipple was about half the bigness of my head, and the hue both of that and the dug, so varied with spots, pimples, and freckles, that nothing could appear more nauseous.
What the clergyman-writer did not realize is that although breasts can have pimples, the areolar bumps that he was probably referring to were sebaceous glands. They secrete a fluid consisting of wax monoesters, triglycerides, free fatty acids and squalene, a terpene also found in shark oil. The Montgomery tubercles, a type of sebaceous gland, play an important role in breastfeeding. Secretions from these pregnancy-enlarged glands lubricate the breasts, protecting them from trauma and infection. Smooth muscle bundles are also found in these glands, which extend into the tips of the breasts. If it were not for those variations that Swift found unappealing, nipples would not pucker up in the cold or during a state of arousal.
Sebum, the mixture of fats released by sebaceous glands, is found in all mammals, and so it also serves to lubricate hair. The exact composition varies among species, but there is one fatty acid that is only released by humans. Appropriately enough, it is called sapienic acid.
Is there any way that the total number of double bonds and structural rings can be predicted from its molecular formula of C16H30O2?
We could use the formula 1+C–H/2= i.u, where i.u.= to the index of unsaturation,
C = number of carbons in the formula,
H = number of hydrogens.
Notice that if the compound contains oxygen, they are ignored. If there had been nitrogen atoms, one hydrogen would have to be removed for every N. Finally if there had been halogens, each would have to be replaced with hydrogen.
In this case, 1+16 -30/2 = 2. And there are indeed two double bonds in the structure of sapienic acid.
From breasts to structural formulas---only in the mind of a chemist!