APPENDIX. 



699 



siderable distance ; and therefore the intrinsic value of the soil, as a dressing, ought 

 to be allowed for as a deduction from expense of carriage in the case of using it 

 in the way of compost. It is very doubtful whether night soil, disinfected 

 sulphuric acid, or sulphate of iron, &c., would form a manure half as good as if it 

 had been mixed with a sufficient quantity of earth in compost. N. 



189, in p. 59. When there are not sufficient of the phosphates in the soil for 

 bones, their application will have a more powerful effect at first, than after long 

 continuance has caused the soil to abound in these. 



193, in p. 60. Inorganic substances, though not found in great quantity in vege- 

 tables (from 1 to 1 per cent, only), are yet essential. Though great part of their 

 action is as solvents, to introduce other substances, yet the plant will not thrive 

 without them. It is found, for instance, in peaty soils, that there is a great defi- 

 ciency of silicates and phosphates ; and that wheat and oats thrive much better on 

 these soils, when bones, containing phosphates, and when wood ashes, decomposed 

 straw, &c., containing silica, are added. The structure of the plant cannot be built 

 up without all the requisites ; and, though not needed in such quantities as the 

 organic substances, and more generally found mixed in the soil, they (the inorganic) 

 are yet essential, as the straw will not stand without its proportion of flint or silica ; 

 and the lime, phosphorus, soda, and potash found in all parts of the plant are indis- 

 pensable. (See 208). Soda is a constituent to a small extent in beans, clover, &c., 

 and even in wheat. 



214, in p. 66. A great many mineral manures may be most cheaply sown 

 with the hand, dry, in the sto^ of powder ; but are more safely distributed well 

 re divided, will do more good, but may be more 



nures can be applied in the bulk, they will always 

 ;s, which are useful only as a saving of expense. 

 poses in the soil, improves its mechanical texture, 

 To such as peat soils, silicate of potash and phos- 

 earth can be added cheaply, it may give these also 

 lured before, as both of these are found in manure), 

 nd permanently improved in its texture. Farm- 

 the inorganic substances needed, improves the 

 , and is most permanently beneficial ; but where 

 this cannot be got sufficiently cheap, or where peculiar deficiencies or excesses 

 occur in the soil, recourse may be had, with a great degree of profit, to inorganic 

 manures in small compass. 



268, in p. 85. The motion of airor wind is caused by colder air replacing warmer; 

 this may cause the cooling effect of breezes in summer. Why the effects of still cold 

 air are not so great as those of air in motion is, because, when in motion, the cold 

 air is constantly replacing that partially heated by the human body. Why motion 

 of heated air should, when uniformly heated, give relief, is not so plain. Why 

 moisture gives relief is connected with electricity. In dry air the electricity of the 

 body accumulates, because dry air is a bad conductor. Moist air, being a good 

 conductor, draws off the excess of electricity, which, when present, was causing a 

 pricking, uneasy sensation ; and, when removed, the body gets more elastic and 

 exhilarated. Motion is undoubtedly of benefit to leaves and stems of plants. 



281, in p. 90 Plants suffer most at a distance from light, when the light is 

 only from the top, or one-sided. This has been called the attraction of light, but 

 is no explanation. In the one-sided light it may be the greater solidifying of the 



