To furnish an idea of the proportions of the consti tuents of flour in good wheat, we shall give the result of an analysis of Mr Edlins. He separated a pound avoirdupois of wheat into the following ingre dients : according to Mr Edlin, crystals of sugar in four-sided prisms, with dihedral summits. (Edlin on Bread Making, page 49.) If this experiment be correct, wheat contains a portion of common sugar. But we have great doubts respecting it,. We scarcely believe it possible to obtain in regular crystals the very small quantity of sugar that must be contained in a pound of wheat by the process described by Mr Edlin, for he merely set the syrup aside to crystallize in a cool place. Common sugar thus treated would concrete into a hard mass, but would not crystallize. We believe that wheat flour contains a portion of saccharine mat ter, but it is's species different from common sugar. We have never, indeed, made any experiments on the sugar of wheat, but we have made a great many on the saccharine matter of barley, which we found si milar in its properties to the sugar into which starch • is converted by being long boiled in very dilute sul phuric acid. There 'is every reason to believe that the sugar in wheat is similar to that in barley.Now, the sugar in barley crystallizes in spheres similar to candied honey.
9. Starch, the first, the most important, and by far the most abundant constituent of wheat flour, is a white, crisp, crystalline-like substance, insoluble in cold water, but forming with hot water a thick paste, which has the property of gluing bodies together. If it be roasted on the fire till it assumes a brown colour, it becomes soluble in water, and acquires the proper ties of gum. If it be boiled for forty-eight hours in water, holding one-hundredth part of its weight of sulphuric acid in solution, it is dissolved and convert ed into a species of sugar. This sugar is heavier than
the starch from which it was formed ; the sulphuric acid remains unaltered ; and no gaseous body is either absorbed or emitted. Hence it has been concluded, that this sugar is merely a combination of starch and water ; and that the acid acts only by promoting the solution of the starch, without which it is incapable of uniting with water. Starch is one of the most nourishing articles of food, and is undoubtedly the portion of the wheat flour that renders bread so nu tritive.
10. The gluten, the second constituent of wheat flour, is but small in quantity when compared with the starch. It is a grey substance, exceedingly elas tic and adhesive. It is not sensibly soluble in water • after it has been collected into an adhesive mass. does it dissolve in alcohol or ether. When dried, it becomes brown and semitransparent, and when thrown on hot coals, emits a smell similar to that of burning horn. If it be put into a vessel, moist, and set in a damp place, it undergoes a species of fermen tation. Bubbles of gas separate from it. After some days it becomes of a much thinner consistence, and then may be employed to agglutinate substances to gether. In about ten days or a fortnight, it acquires exactly the smell and taste of cheese, which it re sembles in every thing but the colour, which is too dark. This caseous fermentation, if the expression may be permitted, distinguishes gluten from all other vegetable bodies with which we are acquainted. It is to the gluten that wheat flour owes the property of being converted into loaf-bread. All other grains are unfit for that purpose, but they become at as soon