From these facts it is quite easy to devise a method of estimating how large a loaf any given flour will produce. The following method is that used by the author. A small quantity of the flour, usually 20 grams, is weighed out and put into a wide mouthed bottle. A flask of water is warmed to 40° C., of this 100 c.c. is measured out, and into it 2½ grams of compressed yeast is intimately mixed, 20 c.c. of the mixture being added to the 20 grams of flour in the bottle. The flour and yeast-water are then mixed into a cream by stirring with a glass rod. The bottle is then placed in a vessel of water which is kept by a small flame at 35° C. The bottle is connected to an apparatus for measuring gas, and the volume of gas given off every hour is recorded. As already mentioned all flours give off about the same volume of gas during the first three hours. After this length of time the volume of gas given off per hour varies greatly with different flours. Thus a flour which will bake a large loaf gives off under the conditions above described about 20 c.c. of gas during the sixth hour of fermentation, whilst a flour which bakes a small tight loaf gives off during the sixth hour of fermentation only about 5 c.c. of gas. Having devised a feasible method of estimating how large a loaf any given flour will make, the problem of the shape and texture still remains. Previous investigators had exhausted almost every possible chemical property of gluten in their search for a method of estimating strength. The author therefore determined to study its physical properties. Now gluten is what is known as a colloid substance, like albumen the chief constituent of white of egg, casein the substance which separates when milk is curdled, or clay which is a well known constituent of heavy soils. Such colloid substances can scarcely be said to possess definite physical properties of their own, for their properties vary so largely with their surroundings. The white of a fresh egg is a thick glairy liquid. On heating it becomes a white opaque solid, and the addition of certain acids produces a similar change in its properties. Casein exists in fresh milk in solution. The addition of a few drops of acid causes it to separate as finely divided curd. If, however, the milk is warmed before the acid is added the casein separates as a sticky coherent mass. Every farmer knows that lime improves the texture of soils containing much clay, because the lime causes the clay to lose its sticky cohesive nature.