248 ON THE VOLATILE OIL OP BETULA LENTA, ETC. 
crystals of a pale yellow color. This substance forms a 
yellow solution with alcohol, which by evaporation leaves 
it in minute crystals of a yellow color. This substance is 
probably formed by the reaction in the receiver, between 
the nitric acid vapour and that of the volatile oil, (which is 
doubtless generated.) It has an acid reaction, and appears 
analogous to the compound formed from the oil by nitric 
acid. When gaultherin is mixed with fuming nitric acid 
and gently heated, a rapid reaction takes place, nitrous acid 
vapours are evolved, and a yellow solution results, which by 
mixture with water and standing, deposits a crop of yellow- 
ish white prismatic crystals. 
The fixed alkalies and alkaline earths have a remarkable 
action on gaultherin, wholly destroying its power of gene- 
rating volatile oil, and converting it into an acid which re- 
mains combined with the base. When gaultherin is boiled 
with a solution of ammonia until the odor of the latter 
ceases to be perceptible, the gaultherin appears to be but 
slightly acted on, as it reacts with the residue of the bark, 
producing the volatile oil. 
If gaultherin be boiled for some time with hydrated pro- 
toxide of lead in water, and the solution filtered, it is 
found to contain lead and reacts alkaline. By adding sulphu- 
ric acid, carefully avoiding an excess, the liquid filtered from 
the sulphate of lead is acid, and does not contain sulphuric 
acid. But a small part of the gaultherin is decomposed. 
The process of Piria for combining salicin with oxide of 
lead was tried with gaultherin, by rendering a solution of 
the latter alkaline with ammonia, and adding subacetate of 
lead. The gaultherin was thrown down in combination 
with the oxide of lead, but it appears to be either converted 
into gaultheric acid, or otherwise decomposed, as neither 
the liquid filtered from the precipitate, or that obtained by 
decomposing the precipitate with dilute sulphuric acid, 
would yield the volatile oil when mixed with the residue of 
the bark. 
