THE FARMER'S MAGAZINE. 



381 



" This is pumped up at a certain rate into a long 

 cylindrical nearly horizontal iron vessel, traversed 

 by an axis carrying? arms arranged spirally upon 

 it, and into the same end of this vessel a series 

 of cups on endless chains delivers at a correspond- 

 ing rate the mixed coi)rolite powder and bone- 

 dust on which the acid is to operate. A continuous 

 stream of these several ingredients thus enters 

 this cylinder at one end, slowly traverses its en- 

 tire length, being mingled as it goes, and then 

 flows out thoroughly incorporated. The machine 

 is in the roof of the building, so that the mixed 

 material can be conducted in sloping troughs to 

 any apart of the iloor. And as, after all, the princi- 

 pal feature of a manufactory is its character as a 

 warehouse, first for the materials, and next for the 

 result of their process, an immense surface is 

 covered over by roofing, under which the mixed 

 ingredients gradually accumulate, forming a mass 

 some 12 to 16 feet thick, where it lies until it is quar- 

 ried out, broken small, and packed in bags. Many 

 thousand tons thus lie in store, and the process of 

 manufacture, is, no doubt, most thoroughly com- 

 pleted in the old heaps, which are thus awaiting 

 the pick-axe and shovel of the quarryman. 



I have on several occasions warned the farmer 

 against employing adulterated mamires. Several 

 modes of avoiding such wretched mistakes have 

 been often suggested : analyzations — guarantees, 

 have been in vain demanded ; still there is ever 



some loop-hole, through which the fraudulent 

 dealer escapes ; and whatever amount of loss the 

 l)urchaser sustains, he too often finds that he has 

 been dealing with irresponsible and ignorant 

 makers ; the analysis produced, perchance, relates 

 to other specimens than that of the manure sold, 

 the superphosphate of lime is very likely to be 

 made entirely from coprolites and mixed with gyp- 

 sum ; nitrate of soda is frequently adulterated 

 with suli)hate of soda or common salt; guano is 

 still mixed with the Ej)ping clay. There is, in fact, 

 only one safe track for the farmer to follow, and 

 that is by dealing only with first-class firms of long- 

 established reputation. If he is ever tempted by 

 cheap bargains in established manures, let him be 

 well assured, that however profitable it may be to 

 the dealer, it will be almost invariably a dear pur- 

 chase to the deluded agriculturist. 



In taking such a retrospective view of the em- 

 ployment of artificial fertilizers, we may not only 

 glean useful information for our future guidance, 

 but, moreover, we may be well led to conclude that 

 still greater advances are yet to be made. It is 

 evident that our knowledge of the food of plants, 

 of their earthy and organic portions, is but in its 

 infancy. Certain effects produced by currents of 

 air, and by the application of particular saline sub- 

 stances, are now just as much in need of explana- 

 tion to us, as all vegetaljle chemistry was to jethro 

 TuU and Arthur Young. 



ON TOP-DRESSING LAND WITH MARL, CLAY, &c. 



Top-dressing of land means the laying on the 

 surface of the ground of such substances as are 

 known to increase the quantity of the vegetable 

 produce which grows from the soil. It may be 

 very reasonably supposed that this mode of using 

 fertilizing substances would precede the application 

 of them under the soil, or mixed with it; as the 

 effects of substances accidentally dropped on the 

 ground would first attract observation, and would 

 suggest the use of the acting materials in that way, 

 and also the modes that were subsequently adopted. 



The very oldest writers on agriculture do not 

 mention manures at all, and thovigh their successors 

 notice it as a most essential part of cultivation, we 

 are left in utter ignorance in what way the dung 

 was applied to the land. Since the earliest records 

 of modern agriculture, the mode of using manure 

 by spreading it on the surface of the ground has 

 always held a very prominent place, and even at 

 the present day of agricultural advancement, it 

 forms the manner of using fertilizing substances 

 that is imperatively directed by the nature of the 

 materials that are used, and not far from bemg 

 sanctioned as the most beneficial mode by the 

 results of practice and the investigation of science. 

 Observation both intuitive and practical has ever 

 acknowledged that all fertilizing substances that 

 are reduced in particle, and minute in coherence, 

 are most economically used by being spread over 

 the surface of the ground, as the distance between 

 the elements is more reduced, and affords more 



opportunities for combinations and reciprocal 

 affinities. The materials that are more gross in 

 nature and larger in bulk, require to be reduced by 

 preparation, and mixed in opposite qualities in 

 order to attain a state of minute adherence. Ex- 

 perience has ever recorded the fact that the effects 

 of substances used as manures on the surface of 

 the ground, are in a direct ratio with the minute 

 or aggregated form in which they exist : or they 

 are efficacious, or they fail in effect, according as 

 they are reduced in particle or concreted into 

 masses. All chemical combination is the result of 

 elective attraction, and bodies unite according to 

 the distances at which the power is exerted. It is 

 a general law that the efficacy is in the inverse 

 ratio of the affinity of aggregation ; for this latter 

 power holds together the homogeneous particles, 

 and prevents their separating and joining the parts 

 of another body ; and the greater the power is, the 

 less efficacious must be the affinity of composition. 

 Bodies combine from being in opposite electrical 

 states, and decomposition consequently proceeds 

 from the same electrical condition. This action 

 cannot take place unless the substances be mixed 

 in the most intimate manner, and it happens only 

 betv/een the ultimate particles of bodies, and at 

 insensible distances; if the attraction of cohesion 

 only happens, in which the bodies retain the qualities 

 they possessed before they were joined, and can be 

 separated by mechanical force, there will be wanting 

 the combination that results from the uniting of 



