84 



AGRICULTURAL CHEMISTRY. 



quantities of inorganic ingredients. This 

 subject has been left unexamined by Spren- 

 gel, yet it is one of much importance ; for 

 the application of manures must be regulated 

 by the composition of the plants which are 

 cultivated on any particular soil. Still the 

 composition of the soil must always be kept 

 in view. Thus it would be perfect extrava- 

 gance to manure certain soils with marl, 

 ashes, or gypsum ; whilst, on the contrary, 

 these compounds would produce the most 

 beneficial results on other lands. 



In a former part of the work, the princi- 

 pal action of gypsum upon vegetation was 

 ascribed to the decomposition and fixation 

 of the carbonate of ammonia contained in 

 rain-water; but gypsum exerts a twofold 

 action. The power of decomposing car- 

 bonate of ammonia, and of fixing the am- 

 monia, is not peculiar to gypsum, but is 

 shared also by other salts of lime (chloride 



of calcium, for example.) But it acts also 

 as a sulphate, and when useful as such can- 

 not be replaced by any other salt of lime 

 which does not contain sulphuric acid. 



Hence gypsum can be replaced as a ma- 

 nure only by a mixture of a salt of lime 

 with ammonia, and a salt of sulphuric acid. 

 Sulphate of ammonia can therefore be sub- 

 stituted for gypsum, and exerts a more rapid 

 and effectual action. In France, sulphuric 

 acid has been poured upon the fields after 

 the removal of the crops, and has been 

 found to form a good manuie. But this is 

 merely a process for forming gypsum in 

 situ ; for the soils upon which it is applied 

 contain much lime, which enters into com- 

 bination with the sulphuric acid. It would 

 certainly be much more advantageous to 

 form sulphate of ammonia by adding the 

 acid to putrefied urine, and to apply this 

 mixture to the field. 



APPENDIX TO PART I. 



EXPERIMENTS AND OBSERVATIONS ON THE ACTION OF CHARCOAL FROM 

 WOOD ON VEGETATION. BY EDWARD LUKAS.* 



" IN a division of a low hot-house in the 

 botanical garden at Munich, a bed was set 

 apart for young tropical plants, but instead 

 of being filled with tan, as is usually the 

 rase, it was filled with the powder of char- 

 coal f y. rrwfria.-. "vhich could be easily pro- 

 cured,) tne A arge pieces of charcoal having 

 been previously separated by means of a 

 sieve. The heat was conducted by means 

 of a tube of white iron into a hollow space 

 in thjs bed, and distributed a gentle warmth, 

 such as tan communicates, when in a state 

 of fermentation. The plants placed in this 

 bed of charcoal quickly vegetated, and ac- 

 quired a healthy appearance. Now, as is 

 always the case in such beds, the roots of 

 many of the plants penetrated through 

 the holes in the bottom of the pots, and 

 then spread themselves out ; but these 

 plants evidently surpassed in vigour and 

 general luxuriance plants grown in the 

 common way for example, in tan. Seve- 

 ral of them, of which I shall only specify 

 the beautiful TJmnbergia alata, and the ge- 

 nus Peireskice, throve quite astonishingly; 

 the blossoms of the former were so rich, 

 that all who saw it affirmed they had never 

 before seen such a specimen. It produced 

 a l*o a number of seeds without any artificial 

 aid, while in most cases it is necessary to 

 apply the pollen by the hand. The Peires- 

 kice grew so vigorously, that the P. aculeata 

 produced shoots several ells in length, and the 

 P. grandifolia acquired leaves a foot in length. 

 These facts, as well as the quick germina- 

 tion of the seeds which had been scattered 

 spontaneously, and the abundant appearance 

 of young Filices, naturally attracted my at- 

 tention, and I was gradually led to a series 



* See page 27. 



of experiments, the results of which may 

 not be uninteresting ; for, besides being of 

 practical use in the cultivation of most 

 plants, they demonstrate also several facts 

 of importance to physiology. The first ex- 

 periment which naturally suggested itself 

 was to mix a certain proportion of charcoal 

 with the earth in whicn different plants 

 grew, and to increase its quantity according 

 as the advantage of the method was per- 

 ceived. An addition of f charcoal, for exam- 

 ple, to vegetable mould, appeared to answer 

 excellently for the Gesnena and Gloxinia, 

 and also for the tropical Jlroidece, with tube- 

 rous roots. The first two soon excited the 

 attention of connoisseurs, by the great 

 beauty of all their parts and their general 

 appearance. They surpassed very quickly 

 those cultivated in the common way, both 

 in the thickness of their stems and dark 

 colour of their leaves ; their blossoms were 

 beautiful, and their vegetation lasted much 

 longer than usual, so much so, that in the 



| middle of November, when other plants of 

 the same kinds were dead, these were quite 

 fre'sh and partly in bloom. Jlroidece took 

 root very rapidly, and their leaves surpassed 

 much in size the leaves of those not so 

 treated; the species which are reared as 

 ornamental plants on account of the beauti 

 ful colouring of their leaves, (I mean such 

 as the Caladium bicolor, Pictum, Pcecile, 

 &c.,) were particularly remarked for the 

 liveliness of their tints ; and it happened 

 here also, that the period of their vegetation 



I was unusually long. A cactus planted in a 



! mixture of equal parts of charcoal and earth 

 throve progressively, and attained double of 

 its former size in the space of a few weeks. 



. The use of the charcoal was very advan- 



