188S] 



FARMERS' REGISTER. 



641 



ter : (he grass watered with solutions of jelly, su- 

 gar, and mucila<re, grew most vigorously ; and 

 ihat watered with the solution oflhe tanning prin- 

 ciple grew better than thai watered with common 

 water. 



I endeavored to a.sccrtain wheiher soluble ve- 

 getable substances passed in an unchanged slate 

 into the roots of plants, by comparing the products 

 of the analysis of the roots of some plants of 

 mint which had grown, some in common water, 

 some in a solution of sugar : 120 grains of the 

 roots of the mint which grew in the solution o( 

 sugar oflbrdcd five grains of pale green extract, 

 which had a sweetish taste, but which slightly 

 coagulated by the action of nicohol : 120 grains 

 of the roots of tiie mint which had grown in com- 

 mon water yielded three grains and a half of ex- 

 tract, which was of a deep olive color ; its taste 

 was sweetish, but more astrinjrent than that of the 

 other extract, and it coagulated more copiously 

 with alcohol. 



These results, though not quite decisive, favor 

 the opinion that soluble matters pass unaltered into 

 the roots of plants ; and the idea is confirmed by 

 the circumstances that the radical fibres of plants 

 made to trrow in inlLisions of madder are tinned 

 red ; and it may be considered as almost proved 

 by the diet, that substances which are even poi- 

 sonous to vegetables are absorbed by them. [ 

 introduced the roots of a primrose into a weak 

 solution of oxide of iron in vinegar, and suffered 

 it to remain in it till the leaves became yellow; the 

 roots were then carefully washed in distilled wale'*, 

 bruised, and boiled in a small quantity of the same 

 fluid : the decoction of them passed through a filler 

 was examined by the test of infusion of nutiralls; 

 the decoction gained a sironirtint of purple, which 

 proves that solution of iron had been taken up by 

 the vessels or pores in the roots. 



Vegetable and animal subgtanccs deposited in 

 the soil, as i« shown by universal exf^erience, are 

 consumed during the process of veiretation ; and 

 they can only nourish the plant by aflbrding solid 

 matters capable of being dissolved by water, or 

 gaseous substances capable of being absorbed by 

 the fluids in the leaves of vefretables ; but such 

 parts ol" them as are rendered gaseous, and that 

 pass into the atmosphere, must produce a compa- 

 ratively small effect; Irir cases soon become diffused 

 through the mass of the surroundinfj air. The 

 great object in the application of manure should 

 be to make it afford as much soluble matter as 

 possible to the roots of the plant: and that in a 

 slow and gradutd manner, so that it may be en- 

 tirely consumed in lorming its sap and organized 

 parts. 



Mucilaginous, fjelatinous, saccharine, oily and 

 extractive fluids, and solution of carbonic acid and 

 water are substances that in their unchanged 

 states contain almost all the principles necessary 

 for the lifti of plants ; but there are few cases in 

 which they can be applied as manures, in their pure 

 forms ; and vegetable manures, in general, contain 

 a great excess of fibrous and insoluble matter, 

 which must undergo chemical changes before they 

 can become the food of plants. 



It will be proper to take a scientific view of the 

 nature of these changes ; of the causes which oc- 

 casion them, and which accelerate or retard them; 

 and of the products they afford. 



If any li-esh vegetable matter which contains 

 Vol. VI.— 81 



sugar, mucilage, starch, or other of the vegetable 

 compounds soluble in water, be moistened and ex- 

 posed <o air, at a tcnipcraturc from 55° to 80°, 

 oxygen will soon be absorbed, and carbonic acid 

 formed ; heat will be produced, and elastic fluids, 

 principally carbonic acid, gaseous oxide of carbon, 

 and hydro-carbonate will be evolved ; a dark-co- 

 lored liquid, of a slightly sour or bitter taste, wiU 

 likewise be formed ; and if the process be suffered 

 to continue lor a lime sufficiently long, nothing 

 solid will remain, except earthy and saline matter, 

 colored black by charcoal. 



The dark-colored fluid formed in the ferment- 

 ation always contains acetic acid; and when albu- 

 men or gluten exists in the vesetable substance, it 

 likewise contains volatile alkali. 



In proportion as there is more gluten, albumen, 

 or matters soluble in water, in the vegetable sub- 

 stances exposed to fermentation, so in proportion, 

 all othercircumstances being equal, vvillthe process 

 be more rapid. Pure woody fibre alone undergoes 

 a change very slowly; but its texture is broken 

 down, and it is easily resolved into new elements 

 when mixed with substances more liable to change, 

 containing more oxygen and hydrogen. Volatile 

 and fixed oils, resins and wax, are more susceptible 

 of change than woody fibre when exposed to air 

 and water, but much less liable than the other 

 vegetable compounds ; and even the most inflam- 

 mable substances, by the absorption of oxygen, be- 

 come gradually soluble in water. 



Animal matters in general are more liable to 

 decompose than vegetable substances; oxygen is 

 absorbed, and carbonic acid and ammonia formed 

 in the process of their putrefaction. They pro- 

 duce foetid compound elastic fluids, and likewise 

 azote: they afford dark-colored acid, and oily fluids 

 and leave a residuum of salts and earths mixed 

 with carbonaceous matter. 



The principal substances which constitute the 

 different parts of animals, or which are found in 

 their blood, their secretions, or their excrements, 

 are gelatine, fibrine, mucus, fatty or oily matter, 

 albumen, urea, uric acid, and different acid, saline, 

 and earthy matters. 



Ofthese ge/flfme is the substance which when 

 combined with water forms jelly. It in very liable 

 to putrefaction. According to MM. Gay Lussac 

 and Thenard, it is composed of 



47-88 of carbon. 

 27-207— oxygen. 

 7-914 — hydrogen. 

 16-998— azote. 



These proportions cannot be considered as de- 

 finite, for they do not bear to each other the ratios 

 of any simple multiples of the number represent- 

 ing the elements; the case seems to be the same 

 with other animal compounds: and even in vege- 

 table substances in general, as appears from the 

 statements given in the third lecture, the propor- 

 tions are far from havingthe same simple relation.s 

 as in the binary compounds capable of being made 

 artificially; such as acids, alkalies, oxides, and in 

 salts. 



Fibrine constitutes the basis of 'he muscular 

 fibre of animals, and a similar substance may be 

 obtained from recent fluid blood ; by stirring it 

 with a stick the fibrine will adhere to the stick. 

 It is not soluble in water; hut by the action of 

 acids, as Mr. Hatchett has shown, it becomes so- 

 luble, and analogous to gelatine. It is less dia- 



