Barton, Benjamin Smith, 1766-1815. Benjamin Barton Smith notebook on materia medica circa 1796-1798. B MS b52.1, Countway Library of Medicine.

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Materia Alimentaria

Milk

corodes copper which it does not when sweet, from these facts I am induced to believe the rancidity is owing to the presence of an acid. During the process of churning I believe there is a disengagement of carbonic acid, owing to a decomposition of the milk. The Hottentots make their butter by pouring their milk into leather bags made for the purpose and shaking them until the butter is found. Sugar and Nitre preserve it sweet for a long time, the acid found in butter is the sebacic. Mr Russell tells of a plant in India which deprives butter of its rancidity and when mixed with it preserves it. Rennet is very often used to coagulate milk. Dr Young thought this not to depend on an acid, for when mixed with Volatile Alkali it still preserves this property, also the liver and heart of a turkey, some live fish have this property which they loose when dead, some vegitables will likewise coagulate milk. The milk of herbivorous animals is coagulated by the nitrous acid but that of the carnivorous is not. Rennet I think coagulates milk by the acid it contains, by the same means do children coagulate milk, many authors suppose milk to be only renovated chyle,

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Materia Alimentaria

Milk

but to this I object, I believe it to be a secretion as much as any other fluid in the animal body, chese [cheese] when distilled yields ammonia since it has been supposed of an animal nature but many vegitables as the horse radish yield it also, this fluid seems to be an intermediate between animal and vegitable matter by distillation it also yields hydrogen, carbonic acid &c. Milk whey contains seven eighths of an aqueous matter, it contains a small matter of oil and cheese, it contains also a sacharin matter which may be obtained by evaporation to the consistency of honey drying, dissolving, and adding the whites of eggs to clarify it, the acid is obtained from the sugar called Saclactic acid by fermentation, to effect this some water is to be added to some sound sour milk, after standing some time it is to be beat with a spatula untill all the parts are well united it must be frequently agitated for twenty four hours, this agitation is esentially necessary for fermentation, thus the Arabs make an intoxicating liquor from mares milk, which yields of distillation an third alkohol, the proportion of cheese is greater in ruminating animals, the proportion of the oily

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