The Chemistry of Cookery

which it contains. This rises as it becomes solidified, carrying with it some of the fat globules of the milk, and a little of its sugar and saline constituents, thus forming a skin-like scum on the surface, which may be lifted with a spoon and eaten, as it is perfectly wholesome, and very nutritious. If all the milk that is poured into London every morning were to flow down a single channel, it would form a respectable little rivulet. An interesting example of the self-adjusting operation of demand and supply is presented by the fact that, without any special legislation or any dictating official, the quantity required should thus flow with so little excess that, in spite of its perishable qualities, little or none is spoiled by souring; and yet at any moment anybody may buy a pennyworth within two or three hundred yards of any part of the great metropolis. There is no record of any single day on which the supply has failed, or even been sensibly deficient. This is effected by drawing the supplies from a great number of independent sources, which are not likely to be simultaneously disturbed in the same direction. Coupled with this advantage is a serious danger. It has been demonstrated that certain microbia (minute living abominations), which are said to disseminate malignant diseases, may live in milk, feed upon it, increase and multiply therein, and by it be transmitted to human beings with possibly serious and even fatal results. This general germ theory of disease has been recently questioned by some men whose conclusions demand respect. Dr. B. W. Richardson stoutly opposes it, and in the particular instance of the ‘comma-shaped’ bacillus, so firmly described as the origin of cholera, the refutation is apparently complete. The alternative hypothesis is that the class of diseases in question are caused by a _chemical_ poison, not necessarily organised as a plant or animal, and therefore not to be found by the microscope. I speak the more feelingly on this subject, having very recently had painful experience of it. One of my sons went for a