The way to see the important effect of fermentation on flavour is to compare a loaf raised naturally by the gas produced by yeast with the loaf that is raised by gas, which is prepared outside and then pumped in, as in some systems, or with a loaf that is raised by adding chemicals. The extent of the fermentation, rather than its rapidity, will be the ruling factor in the various differences that there will be between these two extremes. The presence of acid and change, as developed during fermentation, will strike the palate, and give the sensation known as flavour, in proportion as it is concealed or otherwise by other substances. For instance, salt not only has effect on flavour by steadying fermentation, but has a flavour of its own, which, according to the amount added, makes itself apparent, or hides, or counteracts other effects. If added in normal quantities, which in the South of England would be about 3 lbs. per sack, it is not tasted; if added in much smaller quantities the bread would be insipid, unless some other flavour, such as acid, had been developed; if added in quantities of 5 or 6 lbs. per sack, as customary in Scotland, the loaf will have a distinctly salt taste, unless, on the other hand, it should be largely covered by an excess of acid often produced by long processes.