The kitchen is a chemical laboratory in which are conducted a number of chemical processes by which our food is converted from its crude state to a condition more suitable for digestion and nutrition, and made more agreeable to the palate. It is the _rationale_ or _ology_ of these processes that I shall endeavour to explain; but at the outset it is only fair to say that in many instances I shall not succeed in doing this satisfactorily, as there still remain some kitchen mysteries that have not yet come within the firm grasp of science. The _whole_ story of the chemical differences between a roast, a boiled, and a raw leg of mutton has not yet been told. You and I, gentle reader, aided by no other apparatus than a knife and fork, can easily detect the difference between a cut out of the saddle of a three-year-old Southdown and one from a ten-months-old meadow-fed Leicester, but the chemist in his laboratory, with all his reagents, test-tubes, beakers, combustion-tubes, potash-bulbs, &c. &c., and his balance turning to one-thousandth of a grain, cannot physically demonstrate the sources of these differences of flavour. Still I hope to show that modern chemistry can throw into the kitchen a great deal of light that shall not merely help the cook in doing his or her work more efficiently, but shall also elevate both the work and the worker, and render the kitchen far more interesting to all intelligent people who have an appetite for knowledge, as well as for food; more so than it can be while the cook is groping in rule-of-thumb darkness—is merely a technical operator unenlightened by technological intelligence. In the course of these papers I shall draw largely on the practical and philosophical work of that remarkable man, Benjamin Thompson, the Massachusetts ’prentice-boy and schoolmaster; afterwards the British soldier and diplomatist, Colonel Sir Benjamin Thompson; then Colonel of Horse and General Aide-de-Camp of the Elector Charles Theodore of Bavaria; then Major-General of Cavalry, Privy Councillor of State and head of War Department of Bavaria; then Count Rumford of the Holy Roman Empire and Order of the White Eagle; then Military Dictator of Bavaria, with full governing powers during the absence of the Elector; then a private resident in Brompton Road, and founder of the Royal Institution in Albemarle Street; then a Parisian _citoyen_, the husband of the ‘Goddess of Reason,’ the widow of Lavoisier; but, above all, a practical and scientific cook, whose exploits in economic cookery are still but very imperfectly appreciated, though he himself evidently regarded them as the most important of all his varied achievements. His faith in cookery is well expressed in the following, where he is speaking of his experiments in feeding the Bavarian army and the poor of Munich. He says: