The analysis of bread is conducted essentially in the same manner as that of flour. Under ordinary circumstances, the determinations required are limited to an estimation of the moisture contained in the crumb, the amount of the ash, and special tests for the presence of alum and copper salts. Owing to the broken condition of the starch granules in bread, their identification by the microscope is usually rendered exceedingly difficult. The logwood test for alum in bread is applied by Bell as follows:--About 10 grammes of the crumb are immersed in a little water containing 5 c.c. each of the freshly prepared logwood tincture and solution of ammonium carbonate for about five minutes, after which the liquid is decanted, and the bread dried at a gentle heat. In the presence of alum the bread will acquire the characteristic lavender tint mentioned under Flour. It should be added, that salts of magnesia also produce a lavender lake with alum; but this fact does not affect the usefulness of the process as a preliminary test to the quantitative determination of the mineral impurities present in the sample under examination. The quantitative examination of alum in bread is made by one of the methods described on p. 93. Bread, free from alum, will sometimes yield 0·013 per cent. of aluminium phosphate, and this amount should therefore be deducted from the weight of the precipitate obtained. The average of the results obtained by Dr. Edward G. Love, New York State Board of Health, from the examination of the crumb of ten samples of the cheaper varieties of wheaten bread were as follows:-- Per cent. Water 42·80 Total ash 1·0066 Silica and sand 0·0056 Aluminium (and ferric) phosphates 0·0053 That the addition of alum to bread is prevalent seems to admit of little doubt. The British Public Analysts, in 1879, tested 1287 samples of bread, of which 95 (or 7·3 per cent.) contained alum. Of 18 samples examined, in 1880, in the city of Washington, 8 were adulterated with the salt. The question of the sanitary effects produced by the use of alumed bread is one which has given rise to very extended discussion. According to some authorities, the conversion of alum into an insoluble salt by the fermentation process, which takes place in bread-making, is regarded as a proof that it remains inert, and is consequently harmless in its effects. Others contend that its action as a preventive of excessive fermentation is at the expense of valuable nutritious constituents of the flour, and that its combination with the phosphates present in the grain results in the formation of an insoluble salt which tends to retard digestion. Experiments have been made by J. West Knights, on the comparative action of artificial gastric juice upon pure and alumed bread, which apparently support this latter view.