2^6 



PIIYTOCIIEMV. 



ing sap of vegetables. Azote is produced in the cai'th, partly 

 Iroiii the corrupted refuse of animals, partly from the clay or 

 loam which in a greater or less quantity are mixed with the soil 

 or mould, and partly, in the last place, from the atmosphere, 

 which, in three out of four parts, is composed of azote. The 

 advantage of a certain portion of clay in the soil, is not only 

 evident from this circumstance, but also from the further 

 consideration, that it retains the moisture for a longer time, 

 and supplies it to tlie roots. 



Azote appears also to be taken up into plants from ma- 

 nures. Tobacco derives its pungent taste and unpleasant 

 flavour from animal manure. Grain produced on land 

 highly manured with sheep dung, contains too mucli gluten 

 to be employed in the brewing of ale. Manure composed 

 of the refuse of animals, as pieces of horns and claws, pro- 

 duces abundance of straw fit for litter, but little meal, and too 

 much gluten. 



349. 



it having been shewn, that the moisture drawn up by 

 })lants is only carbonic acid-water impregnated with azote, 

 the crude ascending sap of plants must have in a great de- 

 gree the same composition ; and the only difference will be, 

 that the living principle has operated upon the fluid, and has 

 mixed it, the higher it has ascended, with the greater num- 

 ber of peculiar vegetable matters. 



In fact, the crude ascending sap exhibits properties which 

 completely confirm this account. As it mounts in the inner 

 bark of trees, it appears as a clear fluid, of a pleasant taste, and 

 producing a titillating eflect upon the tongue. It easily fer- 

 ments, and evolves during tliis process carbonic acid gas, which, 

 when united with hydrogen, is known as an intoxicating drink. 

 If the fermentation is continued, azote is disengaged, Avhich 

 swims upon the surface, and the liquor itself becomes of the 

 taste of vinegar. As this composition of the ascending sap is 

 the same in almost all plants, it is evident that it is directly 

 derived from the moisture of the earth, and that it is distin- 

 guished from it only by the oxygenised slimy matter which 

 it has attracted. 



