S8s Dr. Prout on the ultimate composition 
but actual powder; and after being repeatedly subjected to 
the heat of an oven, was ground in the usual manner of com. 
Wood thus prepared, according to the author, acquires the 
smell and taste of corn flour. It is however never quite 
white, but always of a yellowish colour. It also agrees with 
corn flour in this respect, that it does not ferment without the 
addition of leaven, and in this case sour leaven of corn flour 
is found to answer best. With this it makes a perfectly 
uniform and spongy bread ; and when it is thoroughly baked, 
and has much crust, it has a much better taste of bread than 
what in times of scarcity is prepared from the bran and husks 
of corn. Wood flour also, boiled in water, forms a thick tough 
trembling jelly, like that of wheat starch, and which is very 
nutritious.* 
It may be remarked that all the preceding principles are 
capable of being converted into oxalic acid by the action of 
the nitric acid, and into sugar by the action of dilute sul- 
phuric acid. 
Acetic Acid, or Vinegar. 
This principle seems to have been more or less used as an 
aliment, either by accident or design, in every age and country. 
There have been various analyses of it published, by different 
chemists ; but it is singular, that although some of them have 
given its exact composition, no one seems to have been struck 
with the most remarkable peculiarity of its composition ,-f viz. 
* See the Edinburgh Magazine for November 1817, p. 313, where an account 
is also given of the Lapland mode of making bread from the bark of trees, as 
described by Von Buch. It is not improbable that during the above processes 
the lignin combines with water, and forms an artificial starch. 
•j- Berzelius, in his Paper On the definite proportions, in which the elements 
