The best method to pursue in buying flour is, first, to find a good dealer, upon whose advice you may rely. Next, take a sample of the flour recommended and, with a recipe which you have _proved_ to be correct, try some; if the first loaf of bread is not satisfactory, try another, and then another, until you are confident that the fault lies in the flour, and not in the method of making. Finally, having found a brand of flour from which you can make yellow-white instead of snow-white bread, which has a nutty, sweet flavor, which in mixing absorbs much liquid, and does not "run" after you think you have got it stiff enough, and which feels puffy and elastic to the hand after molding, keep it; it is probably good. Often the same flour is sold in different sections of the country under different names, so that it is impossible to recommend any special brand. Each buyer must ascertain for herself which brands in her locality are best. It is just as easy to have good bread as poor. It only requires a _little_ care and a _little_ intelligence on the part of the housekeeper. Having found a brand of good flour, next give your attention to yeast. In these days, when excellent compressed yeasts may be found in all markets, it is well to use them, bearing in mind that they _are_ compressed, and that a very small quantity contains a great many yeast cells, and will raise bread as well, if not better, than a large amount. Home-made liquid yeast is exceedingly easy to prepare. It simply requires a mixture of water and some material in which the plant cells will rapidly grow. Grated raw potato, cooked by pouring on boiling water, flour, and sugar form an excellent food for their propagation. A recipe for yeast will be given later. Now we have come to the consideration of what will take place when the two, flour and yeast, are made into dough. According to some accounts of the subject, the yeast begins to act first upon the starch, converting it into sugar (glucose C_{6}H_{12}O_{6}). While this is taking place there is no _apparent_ change, for nothing else is formed except the glucose, or sugar. Then this sugar is changed into alcohol and carbonic acid; the latter, owing to its diffusive nature, endeavors to escape, but becomes entangled in the viscous mass and swells it to several times its original bulk. This has been the accepted explanation; it is now, however, believed not to be correct. It is thought, and I believe demonstrated, that the yeast plant lives upon sugar; that it has not the power to act directly upon starch, but that it is capable of _producing_ a substance which acts upon starch to convert it into sugar. The production of the carbonic acid is the end of desirable chemical change, and when it has been carried to a sufficient degree to fill the dough with bubbles, it should be stopped.