XANTHORRH GA. 
It thus becomes a question of the cost of phenol and the cost of the 
large ratio of nitric acid required which it has not ‘been found possible 
to reduce sufficiently to make the'manufacture of picric acid profitable 
from Grass Tree resin in competition with cheap phenol, which requires 
so little purification. The recovery of the nitric acid after the picric 
had been obtained, or by the preparation of the by-products, would 
reduce the cost. But the preparation of by-products depends on the 
development of industries which are not at present established in 
Australia. With cheap synthetie nitric acid and improved methods, 
worked on a large scale, the preparation from resin is a possible 
‘commercial proposition. < 
Tn addition to the question of the production of picric acid from 
the resin, the Imperial Institute has been particularly concerned with 
such questions as— 
(1) The use of the resin for making varnish, and. generally as 
a cheap substitute for shellac. 
(2) The use as a dye. es 
(3) The distillation or fusion with alkali, with a view to the 
production of commercially useful by-products. 
_ X. resin has long been used for making varnish. Locally, it has 
been used as a lacquer for protecting tins for meat preserving, for 
inferior French polish in the furniture trade, and as a colouring for 
varnish used to imitate cedar. The Imperial Institute carried out 
tests with varnish made from the resin, and reported that it had less 
body and was less resistant to the action of air and moisture than 
shellac, though it is superior to common resin. Owing to the present 
high prices of shellac, it is being used in England more extensively for 
cheap spirit varnishes, especiallly those used for floors and common 
wooden articles. In the Farber Zeitung (Germany), December, 1901, 
it is stated that both forms of Grass Tree resin (red and yellow) are 
used in Germany for the preparation of spirit lacquers for coating 
metal, and that the resin in alcohol has replaced the ordinary gold 
lacquer used in coating the brass parts of instruments. In combination 
with copal and shellac, the resins are made into transparent wood 
varnishes, and these can be applied to metals without previous warming, 
and they do not bleach. Mr. J. C. Earl, in his Bulletin on Grass Trees 
(Adelaide, 1917), states that unless the spirit varnish solution is highly 
concentrated, it has little viscosity, and readily soaks into wood. If, 
however, the solution is too concentrated, the surface of the varnish 
shows pronounced “checking” a day or two after application. The 
yereee surface is readily affected by water, and is at all times very 
rittle. : i.e 
The appearance of stains on a resin-varnished surface exposed to 
water or moist conditions for some time was thought to be due to the 
presence in the resin of soluble benzoic and cinnamic, or other acids. 
In order to test this, Mr. Earl removed all free acids from the resin 
by treatment with hot caustic soda solution, under pressure of 25 to 
30 Ibs. This treatment hydrolysed any esters present, and removed any 
acids produced by their hydrolysis. Comparative tests were ‘then made 
with the untreated and the prepared resin varnish; these were poured on 
to glass plates and allowed to thoroughly dry for a few weeks, and were 
then immersed side by side in water. The varnish from the untreated 
285 
