The injurious effect which excessive coffee drinking produces has been attributed both to the caffein and tannin therein. It is a common opinion that a coffee made of partial percolation has a less relative content of tannin and is therefore of better flavor and less injurious. Investigations made by the laboratory of Good Housekeeping show that these opinions are not well founded.1

The data obtained show that the more thorough the extraction the less the proportion of tannin. In a typical test it was shown that in one percolation the percentage of tannic acid in the solids of the extract was 68. When the extract was prepared from the same sample by boiling for some time the percentage of tannin in the solids of the extract was only 54.7. It appears that the tannin in the roasted coffee bean is more soluble than the sum of the other soluble constituents. Moreover, it is interesting to note that more than half of the soluble constitutents of the roasted bean consist of tannin.

There is still another method for making coffee, which is practised largely in the Orient, affording a product known as Turkish coffee. In this method the coffee is ground into as fine a powder as possible. It is then added to the cup, the hot water poured in, and the wholes stirred around until the water is saturated as far as possible. The grounds are left in the cup. This is a more reasonable and economical way of using coffee. All the berry including the oil, sugar and nitrogenous materials are thus utilized for food. Those who are accustomed to drinking Turkish coffee like it even better than that made by the extraction or percolation method.