32 
Conipositiou uf Cheese. 
would obsoiAo, that generally the scientific principles involved 
in the manufacture of cheese are either misstated by scientific 
writers on tlie subject, or but imperfectly recognised by practical 
men. 
These are some of the principal conclusions at which I have 
arrived in the course of my investigation. As it is not my 
intention to write a complete essay on cheese-making, I shall 
at present only endeavour to point out — 1st, some of the chief 
errors made in the process, stating my reasons for speaking 
of them as such ; and 2ndly, to suggest some remedies and safe- 
guards. But, in order to make my subsequent remarks a little 
more intelligible, I must briefly allude to the composition of milk, 
which, as is well known, is not a uniform white liquid, but a 
fluid owing its opaque character to a number of little cream 
globules. Seen under a miscroscope of no very great power, 
milk appears as a colourless fluid in which there are float- 
ing innumerable little white globules or small bags contain- 
ing fatty matter. The butter is encased in these microscopic 
bags or cells, which themselves are comj)osed of very much 
the same material as the curd of milk. These, being lighter 
than water, rise on standing, and are removed as cream. If it 
were possible to separate the cream completely by standing, the 
milk would be almost colourless ; but inasmuch as a certain 
number of milk-globules always remain suspended in milk, 
even after long standing, skimmed-milk is always more or 
less opaque. We must find, therefore, in the cheese made 
from skimmed-milk a certain amount of butter, though much 
less than in whole-milk cheeses. On the removal of the cream, 
the milk becomes bluer and more transparent ; and hence the 
transparent and peculiarly blue appearance of some of the London 
milk is indicative of its poorness. On allowing milk to become 
acid, which it does readily in warm v/eather, one of its con- 
stituents, which, from its sweet taste, is called sugar- of-milk, is 
converted, at least in part, into lactic acid. This change is 
effected by simple transposition of the elementary particles of 
milk-sugar, without anything being added or detracted from 
them. This lactic acid again separates the next constituent, 
the casein or curd of milk, which may also be separated by 
rennet. On the removal of the casein, either artificially by 
rennet or naturally by the lactic acid, we obtain whey ; and, 
provided this whey is perfectly clear and free from all butter 
and curd (which is not generally the case) in our dairies, we 
may, by evaporating the clear liquid, obtain milk-sugar and a 
certain quantity of matter which is incombustible, and consti- 
tutes the ash of milk. These then are the principal constituents 
of milk — curd or casein, butter, milk-sugar, and mineral matters 
