The Chemistry of Cookery

humid substance it touches, a quantity proportionate to its temperature. The steak receiving its heat by convection—_i.e._ the heat conveyed by such hot air, and communicated by contact—would be _desiccated, but not cooked_. This distinction is so important, that I will illustrate it still further, my chief justification for such insistence being that even Rumford himself evidently failed to understand it, and it has been generally misunderstood or neglected. Let us suppose the hot air used for convection cooking to be at the cooking-point, as the hot water in stewing should be, what will follow its application to the meat? Evaporation of the water in the juices, and with that evaporation a lowering of temperature at the surface of the meat, keeping it below the cooking-point. If the air be heated above this, the evaporation will go on with proportionate rapidity. As nearly 1,000 degrees of heat are lost _as temperature_, and converted into expansive force whenever and wherever evaporation of water occurs, the film of hot, dry air touching the meat is cooled by this evaporation, and sinks immediately, to be replaced by a rising film of lighter, hotter, and drier air. This drinks in more vapour, cools and sinks, to give place to another, and so on till the inner juices gradually ooze between the fibres to the porous surface, where they are carried away by the hot, dry air, and a hard, leathery, unmasticable mass of desiccated gelatin, albumen, fibrin, &c., is produced. Now, let us suppose a similar beefsteak to be cooked by radiant heat, with the least possible co-operation of convection. To effect this, our source of heat must be a good radiator. Glowing solids are better radiators than ordinary flames; therefore coke, or charcoal, or ordinary coal, after its bituminous matter has done its flaming, should be used, and the steak or chop may be placed in front or above a surface of such glowing carbon. In ordinary domestic practice it is placed on a gridiron above the coal, and therefore I will consider this case first. The object to be attained is to