The three ingredients chlorine, silica, and soda cannot be considered in the light of essentials to tobacco culture; but the other substances are absolutely indispensable to plant growth, and the absence of any one of these would render a soil incapable of sustaining agricultural vegetation of any kind. “The variation in the percentage of these ingredients depends somewhat upon the fact that the leaves of different crops are unequally developed, and therefore their nutritive needs are unlike; but it is, no doubt, chiefly connected with the fact that the plant takes up from a highly fertilized soil more of each or every element than is essential for growth. The nearly certain conclusion is that every one of the crops analysed contains more of some elements than belongs to its nutrition. It is quite certain that the average of the analyses of the New England tobaccos is fully up to the mark as regards the necessities of the crop. It is, indeed, not improbable that the lowest percentages of each ingredient are quantities sufficient for a perfect crop. Still, it is not proved that lime may not partially take the place of potash, or the reverse. The probability of such a substitution is great upon the face of most of the analyses. As a rule, those which show most potash show least lime and _vice versâ_; but in one sample both ingredients are considerably below the average. The practical issue of these considerations is to give great probability to the view that the tobacco crop is fed unnecessarily (and wastefully?) high.” (Prof. Johnson.) Tobacco is usually characterized as a very exhausting crop. This is not true as regards the amount of nutriment taken from the soil, for in this respect tobacco is less exacting than hay, potatoes, or rye. It demands chiefly potash and lime, with phosphoric acid and nitrogen. Prof. Johnson recommends for the manuring of one acre, besides ploughing in the stalks of the plants, 500 lb. rock guano or 800 lb. fish guano, 500 lb. kainit (potash salts), and 50 lb. quicklime. But surely it cannot be advisable to mix quicklime with an ammoniacal manure like guano; it seems to the writer that gypsum, or spent calcium oxide from gasworks, would be a far preferable medium for conveying lime to the soil.