26 



AGRICULTURAL CHEMISTRY. 



All superabundant nitrogen is eliminated 

 from the body, as a liquid excrement, 

 through the urinary passages ; all solid sub- 

 stances, incapable of farther transformation, 

 pass out by the intestinal canal, and all 

 gaseous matter by the lungs. 



We should not permit ourselves to be 

 withheld by the idea of a vital principle, 

 from considering in a chemical point of view 

 the process of the transformation of the food, 

 and its assimilation by the various organs. 

 This is the more necessary, as the views, 

 hitherto held, have produced no results, and 

 are quite incapable of useful application. 



Is it truly vitality, which generates sugar 

 m the germ for the nutrition of young plants, 

 or which gives to the stomach the power to 

 dissolve, and to prepare for assimilation, all 

 the matter introduced into it ? A decoction 

 of malt possesses as little power to repro- 

 duce itself, as the stomach of a dead calf; 

 both are, unquestionably, destitute of life. 

 But when amylin or starch is introduced 

 into a decoction of malt, it changes, first 

 into a gummy-like matter, and lastly into 

 sugar. Hard-boiled albumen and muscular 

 fibre can be dissolved in a decoction of a 

 calf's stomach, to which a few drops of mu- 

 riatic acid have been added, precisely as in 

 the stomach itself.* (Schwann, Schulz.) 



The power, therefore, to effect transfor- 

 mations, does not belong to the vital prin- 

 ciple : each transformation is owing to a 

 disturbance in the attraction of the elements 

 of a compound, and is consequently a 

 purelv chemical piocess. There is no doubt 

 that this process takes place in another form 

 from that of the ordinary decomposition of 

 salts, oxides, or sulphurets. But is it the 

 fault of chemistry that physiology has hith- 

 erto taken no notice of this new form of 

 chemical action ? 



Physicians are accustomed to administer 

 whole ounces of borax to patients suffering 

 under urinary calculi, when it is known 

 that the bases of all alkaline salts formed by 

 organic acids are carried through the urinary 

 passages in the form of alkaline carbonates, 

 capable* of dissolving calculi (Wohler.) Is 

 this rational'? The medical reports state, 

 that upon the Rhine, where so much cream 

 of tartar is consumed in wine, the only cases 

 of calculous disorders are those which are 

 imported from other districts. We know 

 that the uric acid calculus is transformed 



consideration, that the most approved remedies 

 for counteracting or stopping the progress of this 

 frightful malady are precisely those which are 

 found most efficacious in retarding putrefaction. 

 Thus, it is well known that much relief is afforded 

 by a residence in works in which empyreumatic 

 oils are manufactured by dry distillation, such as 

 manufactories for the preparation of gas or sal-am- 

 moniac. For the same reason, the respiration of 

 wood vinegar (pyroligneous acid,) of chlorine, and 

 certain of the acids, has been recognized as a 

 means of alleviating the disease. 



* This remarkable action has been completely 

 confirmed in this laboratory (Giessen,) by Dr. 

 Vogel, a highly distinguished young physiologist. 



into the mulberry calculus (which contains 

 oxalic acid,) when patients suffering undei 

 the former exchange the town for the coun- 

 try, where less animal and more vegetable 

 food is used. Are all these circumstances 

 incapable of explanation? 



The volatile oil of the roots of valerian 

 may be obtained from the oil generated dur- 

 ing the fermentation of potatoes (Dumas,) 

 and the oil of the Spircea ulmaria from the 

 crystalline matter of the bark of the willow 

 (Piria.) We are able to form in our labor- 

 atories formic acid, oxalic acid, urea, and 

 the crystalline substances existing in the 

 liquid of the allantois of the cow, all pro- 

 ducts, it is said, of the vital principle. We 

 see, therefore, that this mysterious principle 

 has many relations in common with chemi- 

 cal forces, and that the latter can indeed re- 

 place it. What these relations are, it 

 remains for physiologists to investigate. 

 Truly it would be extraordinary if this vital 

 principle, which uses every thing for its own 

 purposes, had alloted no share to chemical 

 forces, which stand so freely at its disposal. 

 We shall obtain that which is obtainable in 

 a rational inquiry into nature, if we se- 

 parate the actions belonging to chemical 

 powers from those which are subordinate to 

 other influences. But the expression " vital 

 principle" must in the mean time be consi- 

 dered as of equal value with the terms spe- 

 cific or dynamic in medicine : every thing is 

 specific which we cannot explain, and 

 dynamic is the explanation of all which we 

 do not understand j the terms having been 

 invented merely for the purpose of conceal- 

 ing ignorance by the application of learned 

 epithets. 



Transformations of existing compounds 

 are constantly taking place during the whole 

 life of a plant, in consequence of which, 

 and as the results of these transformations, 

 there are produced gaseous matters which 

 are excreted by the leaves and blossoms, solid 

 excrements deposited in the bark, and fluid 

 soluble substances which are eliminated by 

 the roots. Such secretions are most abun- 

 dant immediately before the formation and 

 during the continuance of the blossoms; 

 they diminish after the development of the 

 fruit. Substances containing a large propor- 

 tion of carbon are excreted by the roots and 

 absorbed by the soil. Through the expul- 

 sion of these matters unfitted for nutrition, 

 the soil receives again with usury, the car- 

 bon which it had at first yielded to the 

 young plants as food, in the form of car- 

 bonic acid. 



The soluble matter thus acquired by the 

 soil is still capable of decay and putrefaction, 

 and by undergoing these processes furnishes 

 renewed sources of nutrition to another gene- 

 ration of plants; it becomes humus. The culti- 

 vated soil is thus placed in a situation exactly 

 analogous to that of forests and meadows, 

 for the leaves of trees which fall in the forest 

 in autumn, and the old roots of grass in the 

 meadow, are likewise converted into humus 



