Much more suitable arguments at the command of the advocates of a raw diet - at least when they are reasonably applicable - may be found in the undoubted facts of ease of preparation and economy, for both time, trouble, the wages of a cook and the cost of a fire are saved when the food simply requires cleansing to prepare it for consumption. But the plea of economy may be advanced from the other point of view, that a certain percentage of waste is inseparable from the process of cooking; for here we leave the realm of theory and entrench upon that of indubitable fact.

During cooking by the ordinary methods meat loses from 10 to 50 per cent. of its original weight, and although the loss consists mainly of water, both protein and fat contribute their share. A small proportion of the proteins undergoes obscure chemical changes of such a nature that gelatin, nitrogenous extractives, and other substances are produced, and these tend, however slightly, to reduce the nutritive value of the food. Grindley has shown that when meat is cooked in water at 80°-85° C, it matters little whether it be first placed in hot or cold water, thus shattering a widespread belief that it is essential to plunge it at once into boiling water if we desire to prevent the escape of its nutritive juices. In a series of ninety experiments the average loss of protein was 7.25 per cent., being always greatest when the meat was cut into small cubes and cooked for a very long time, and least when a large fat piece of meat was cooked for over two hours.

The loss of fat depends more upon its quality than its quantity, and varies from .6 to 37.4 per cent., the average being 11.7 per cent., and the greatest loss being incurred when the temperature was highest. On the other hand, during experiments on roasting, the loss of fat was very much higher, averaging as much as 34.27 per cent., while that of protein was much lower, amounting on an average to no more than 1.97 per cent. As might have been expected, the higher the temperature and the longer the process was continued, the greater was the loss both of fat and protein, while the larger pieces lost relatively less both in weight and nutritive value than the smaller pieces.

These experiments are doubtless of comparatively little interest to the "raw-fooder," who naturally but seldom includes meat in his diet list, and they have less influence as an argument in favour of the system than those about to be recorded.

During the cooking of vegetables in water the cellulose absorbs water, becomes softer and more easily masticated, and although probably no more digestible, is at least more likely to be attacked by the bacteria in the alimentary canal. The rupture of the cell walls, however, exposes the starch granules to the action of the water, and hence they become swollen, deformed, and more digestible. As, however, all the nutrients in vegetables are not always enclosed in the cells, but in a varying degree exist in solution in the juice, a large proportion of these soluble substances is liable to be lost when the vegetables are cooked in water. This applies especially to the sugars and valuable mineral matters, and even the starches, though insoluble, suffer a certain amount of loss mechanically. The soluble proteins, on the other hand, are coagulated by heat, and are thus to a certain extent conserved; but when the soaking process is conducted in cold water, a large percentage is thereby lost. Hence the advantage of cooking vegetables, where practicable, with the skin on, and where this is impossible, of submitting them to the action of steam, for by these methods the loss is immensely reduced, being in most cases less than 1 per cent.

Some idea of the loss sustained may be derived from a reference to the experiments of Snyder, Frisby, and Bryant. They found that when potatoes were peeled, cut into pieces and soaked in water before boiling, half the total nitrogen - including a quarter of the proteins - was lost. When cooked immediately after immersion in cold water, the loss was three times less, and when plunged at once into boiling water and then cooked, six times less. This last method is not recommended, as some kinds of potatoes are spoiled in the process.

Carrots which had been scraped, cut into pieces and then boiled, lost from 20 to 40 per cent. of the total nitrogen, and 15 to 26 per cent. of the sugar, depending upon the size of the pieces.

Thirty to 40 per cent. of the dry matter of cabbages, including one-third of the total nitrogen and carbohydrates, is lost during the process of cooking, and more than 80 per cent. of the carbohydrates of onions and turnips disappears during boiling.

The lesson to be learned from these experiments is that from the point of view of economy it is judicious to eat vegetables in salads or in soups, where, of course, all their valuable juices are retained, or where they must be cooked in bulk, to utilise one of the many steam-cookers now so fashionable.

It has been stated that all foods contain substances which are injured or destroyed by the application of heat in cooking, and lecithin, which is of such importance in the growth of tissue and blood cells, has been particularly cited as a case in point. But this is certainly overstating the case, because the addition of fresh fruit juices - which contain no lecithin - is alone necessary to nullify the evil effects of subsisting on cooked foods. In the case of scurvy even these are not essential, for provided that fresh meat be supplied, even although it be cooked, the disease will soon vanish under its benign influence.

It has been averred that a raw-food dietary would prevent the appearance of auto-intoxication with all its evil accompaniments, mainly because it would necessarily compel the total exclusion of animal proteins, which are much more readily attacked by putrefactive organisms than vegetable proteins. It is a strange corollary to this statement that milk previously sterilised should be employed as a medium for the conveyance of the counteracting beneficial organisms.