Milk-Analysis : a practical treatise on the examination of milk and its derivatives, cream, butter, and cheese / by J. Alfred Wanklyn.

Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Milk-Analysis : a practical treatise on the examination of milk and its derivatives, cream, butter, and cheese / by J. Alfred Wanklyn. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    18/92 (page 6)
    G Such, then, are the component parts of milk. It remains to be added, that milk has a specific gravity of about 1 -029, at 15 6 C., and that its physical appearance is very peculiar. It is not a clear liquid, being, in point of fact, an emulsion. Left to itself, it by and by becomes surmounted with a whitish layer, well known as cream. When fresh, it is very nearly neutral to test-paper, but is very apt to turn sour from very slight causes. Milk exhibits great constancy of composition ; the effect of variations in the diet of the cow showing itself in the amount of the secretion rather than in its quality. This is very strikingly manifested on making a comparison of the milk yielded by the poor and ill-fed Bengali cow in India with that given by our own highly-fed beasts in this country. Dr Macnamara’s analyses of the milk of the Bengali cows show that it hardly differs from the milk of English cows in quality, whereas in quantity it differs greatly, the yield of milk from the former being a small fraction only of that from the latter. The milk of an animal has probably very much the same constancy of composition as the blood of the animal. It is well known that, by administering water to an animal, we are not able to dilute its blood to any considerable extent. Instead of telling on the blood, the water tells on the perspiration or on the urine, so that from containing four or five per cent, of solids, the urine may become so dilute as to contain only one per cent, of solids. The milk resembles the blood in this respect, and is in contrast with the urine; and by giving an animal an excess of water, we do not dilute its milk, but its urine. As will be readily comprehended, this constancy of com- position is a cardinal fact in milk analysis. If milk were