30 RELATIVE PROPERTIES OF ORGANIC ELEMENTS. 



weight of some of the more important lands of vegetable substance you 

 are in the habit of cultivating : — 



Hay from 



1000* lOOOf 1000* lOOOf lOOOt 1000* lOOOf lOOOf 



The numbers in the above table represent the constitution of the 



plants and seeds, taken in the stale in which they are given to cattle or 



are laid up for preservation, and then dried at 230° Fahrenheit. By 



this drying they lost severally as follows : 



1000 parts of Potatoes . . lost . . . 722 parts of water 

 ditto of Wheat . . — ... 166 ditto 

 ditto of Hay ... — ... 158 ditto 

 ditto of Aftermath Hay — . 136 to 140 ditto 

 ditto of Oats ... — ... 151 ditto 

 ditto ofClover Seed . — .... 112 ditto 

 ditto of Peas ... — ... 86 ditto 

 In crops as they are reaped, therefore, and even as they are given for 

 food, much water is present. When artificially dried, the carbon ap- 

 proaches to one-half of their weight — the oxygen to more than one- 

 third§ — the hydrogen to little more than 5 per cent. — and the nitrogen 

 rarely to more than 2h per cent. These proportions are variable, but 

 they represent very nearly the relative weights in which these elements 

 enter into the constitution of those forms of vegetable matter which are 

 raised in the greatest quantity for the support of animal life. 



Bat, besides the organic part, vegetable substances contain an inor- 

 ganic portion, which remains behind in the form of ash when the plant is 

 consumed by fire, or of dust when it decomposes and disappears in 

 consequence of natural decay. 



In the dried hay, oats, &c., of which the composition is represented 

 in the above table, we see that the quantity of ash is very variable, in 

 oats being as small as 4 per cent., while of hay every hundred pounds 

 left 10 of ash. A sim'ilar difference is observed generally to prevail 

 throughout the vegetable kingdom. Each variety of plant, when 

 burned, leaves a weight of ash, more or less peculiar to itself. Herba- 

 ceous plants generally leave more than the wood of trees — and differ- 

 ent parts of the same plant yield unlike quantities of inorganic matter.JI 



• Boussingault Annates de Chim. et de Phys. (1838) lxvii. p. 20 to 38. 



t Ditto ditto (1839) Lxxt. p. 113 to 136. 



X Ditto ditto (1838) lxix. p. 356. 



§ This will appear no v^ay inconsistent with the statement in the former Lecture, that 

 oxygen constitutes one-half by weight of alHjujn^ plants, when it is recollected that of the 

 water driven oif in drying these plants eight-ninths by weight consist of oxygen, and that 

 600 lbs. of grass, for example, yield only from 80 to 100 lbs. of hay. 



H Thus of the oak, the dried bark left 60 of ash— the dried leaves 53 — tlie dried albumuin 

 4— and the dried wood only 2 parts in a thousand of ash.— X>« Saicssure. 



