114 
Of woody fibre - - - 876 
— tannin - - 51 
— extract - - - 31 
— mucilage - - - 18 
— matter rendered insoluble during 1 
evaporation, probably a mixture of > 9 
albumen and extract ) 
« — loss, partly saline matter - - 29 
To ascertain the primary elements of the differ- 
ent vegetable principles, and the proportions in 
which they are combined, different methods of 
analysis have been adopted. The most simple 
are their decomposition by heat, or their form- 
ation into new products by combustion. 
When any vegetable principle is acted on by 
a strong red heat, its elements become newly ar- 
ranged. Such of them as are volatile are expelled 
in the gaseous form ; and are either condensed as 
fluids, or remain permanently elastic. The fixed 
remainder is either carbonaceous, earthy, saline, 
alkaline, or metallic matter. 
To make correct experiments on the decomposi- 
tion of vegetable substances by heat, requires a 
complicated apparatus, much time and labour, and 
all the resources of the philosophical chemist ; but 
such results as are useful to the agriculturist may 
be easily obtained. The apparatus necessary, is a 
green glass retort, attached by cement to a re- 
ceiver, connected with a tube passing under an in- 
verted jar of known capacity, filled with water. # 
A given weight of the substance is to be heated to 
See Fig. 14. 
