He also rebukes me in a most earnest manner for the alleged misuse of the chemical term "phosphate of potash," which crept into my article in connection with the right use of the term "phosphate of lime," when I referred to the mineral phosphates of Kentucky, Tennessee, and Florida. Technically he is apparently right. There is no permanent form or no natural mineral form of phosphate of potash which can be removed from place to place. Yet my article was revised by an experienced geologist, thoroughly familiar with the chemistry of the soil, before I sent it to you, and he failed to correct this technical error. My own knowledge of chemistry is very limited. It might be inferred, as my irascible correspondent points out, from the manner in which I have called attention to the deposits of mineral phosphates in Kentucky and Tennessee, that I thought these deposits would yield phosphates of lime and phosphates of potash each in a separate movable form, which could not be a fact. Yet my critic will doubtless admit that the soils of many parts of this country are stocked with potash sufficient for a very long period. Many years ago, when I began the study of the cotton plant and its growth, under the leadership of the late Prof. William B. Rogers, I made reference to the existence of the vast supplies of phosphate of lime and potash, which are necessary to the growth of the cotton plant, in the Southern soils. I derived my conception of their origin in the lowlands and plateaus in marine formations from Professor Rogers, and also from the works of Professor Shaler. One may also impute the large amount of potash that is found in the valleys and mountain lands to the disintegration of the gneiss and other rocks of the Appalachian chain, which have never been washed out by glacial action or by glacial streams. If any one has been misled by this slight misuse of chemical terms it may be well to state that phosphate of potash does not exist, and I am told that it can not exist, in a separate removable form. We have not as yet discovered any large deposit or mine like that of Stassfurt, in Prussia, yielding potash in a commercial form in which it can be widely distributed. We import annually thousands of tons of potash from Stassfurt. This deposit was discovered, as I am informed, by accident, and it may be hoped that a similar accident may occur in this country. These mines were originally opened for the production of salt. In boring for salt the product of a stratum above or below the salt, I know not which, was brought up, which was thrown aside as worthless until an inquisitive visiting chemist examined it and thus discovered this great source of potash. We possess enormous beds of salt, of soda, and of alkalies, scattered throughout the area of this country, in connection with which it may be hoped that we may hereafter discover a deposit of mineral potash, or of the mineral from which potash may be derived cheaply and in large quantities.