254* Mr. Donovan on the nature and combinations 
action of nitrons acid on sugar, a bitter substance and malic 
acid were produced together ; that by the farther action of 
nitrous acid, the bitter substance disappeared, and acid ap- 
peared in its stead. 
The foregoing conjectures correspond also with the fact, 
that by the action of certain substances on each other, the 
bitter principle is evolved at the same time with those acids 
which I suppose to have been produced from that compound 
basis : and the appearance of both at the same time may be 
accounted for by admitting that the conversion was not 
complete. Thus, if alcohol be distilled with nitrous acid, a 
liquor is produced which has a sweet taste. If this liquor be 
re-distilled with another portion of acid, a bitter liquor comes 
over. And if this bitter liquor be distilled a third time with 
a fresh portion of nitrous acid, crystals of oxalic acid make 
their appearance in the residuum. This series of changes 
bears a striking resemblance to that produced by the action 
of nitrous acid on sugar. 
' Haussman observed, that when nitric acid is digested with 
indigo, a very bitter substance results, to which Welther 
gave the name of Amer : in this process, oxalic acid is also 
formed. 
The vegetable acids are even formed by the action of 
nitrous acid on animal substances ; in the instance of muscle 
we obtain the abovementioned Amer with oxalic acid. In bile 
the bitter principle is already formed ; when acted on by 
nitrous acid, oxalic acid is produced. 
On examination we shall not be at a loss to find operations 
analogous to some of the preceding, taking place naturally 
in the vegetable kingdom. The Pyrus Malus or common 
