These are sold to the spice grinders under the name of “P. D.” pepper. Pepper adulterants and pepper mixtures,—P. D., pepper dust; H. P. D., hot pepper dust; W. P. D., white pepper dust—consist of such products as the grinder has at hand or can obtain at the lowest price, the mixer requiring only that the colors shall be such as are suitable for his trade. In London, the olive stones are much used, put up in colors of both black and white. Pepper mixtures are sold under the name of “Poivrette or Pepperette.” Their natural color is pale buff, much resembling the middle layer of the pepper berry when ground, and they cannot be distinguished from the pepper by the eye, even with the use of a hand lens, when mixed with a powdered pepper, but with the aid of the microscope with one-sixth or one-eighth objective, it is seen that they consist of pale, dense, lignous cells, being entire and marked with linear air spaces; some are torn and indistinct. Other substances examined showed finely ground clay and brick dust. The presence of pepper husks and charcoal is generally known by the immensely increased proportion of black particles in the field, as appears in Fig. 43, opposite page 25, Chap. III. The true pepper powder, and one in which rice starch is present, is given in Fig. 21 and in Fig. 42, which also gives us an idea of the size of the pepper starch, which is very small as compared with any other kind of starch. Much authority might be quoted on the adulterations of pepper, but enough has been written to give the reader an idea of its vastness. I will next endeavor to give the method of examining peppers microscopically. First, the sieve examination of those particles left upon a forty to sixty-mesh sieve is of value. This examination will frequently reveal the nature of the adulterant or the too large portion of pepper husk.