of Edinburgh, Session 1884-85. 
181 
solvents of urushic acid. Such being the case, an experiment was 
tried to ascertain whether urushic acid dries in an atmosphere 
charged with hydrochloric acid, A glass plate, very thinly coated 
with pure urushic acid, was placed upon a basin containing fuming 
hydrochloric acid under a bell jar, dried after standing two days. 
The urushic acid darkened in colour, and looked somewhat similar 
to the naturally hardened lacquer. When the (3 acid is heated to 
100° C. it merely softens a little, and even at 130° it shows no 
sign of decomposition. It appears that the substance obtained by 
the decomposition of an alkali salt of urushic acid with hydrochloric 
acid is the same body as /3-urushic acid. 
Bromine acts powerfully upon urushic acid, evolving fumes of 
hydrobromic acid. To a solution of the acid in carbon bisulphide 
bromine was gradually added till it was in some excess ; the whole 
being evaporated to dryness over a water-bath the mass was 
exhausted with strong alcohol, and the extract again evaporated, 
after which it yielded a dark semi-solid mass. This was tested for 
bromine by igniting it with pure lime. 0*7060 grammes of the 
substance gave 1*1510 grammes of silver bromide; or bromine was 
shown to be present in amount equal to 69*37 per cent., agreeing with 
a hexabromo substitution derivative of the acid, having the formula 
Ci 4 Hi 2 I> r g0 2 , which requires 69*36 per cent, of bromine. At 
ordinary temperatures it is an almost solid body of a brownish 
colour, and soluble in most solvents of urushic acid. By using 
regulated quantities of bromine its lower substitution products might 
perhaps be obtained. Chlorine also gives a series of substitution 
products ; but the compounds have not yet been fully examined. 
The action of nitric add upon urushic acid gives rise first to a 
series of nitro-substitution products, which appear to change after- 
wards into another acid containing more oxygen. The reaction is 
very energetic ; the urushic acid first swells up to about thirty times 
its original bulk in the form of a yellowish sponge, which disappears 
gradually with the progress of the reaction. A quantity of this 
porous body was heated for half a day, treated with a large quantity 
of water, dissolved in alcohol, and precipitated with ferric chloride. 
The precipitate, after the usual purification and drying, was 
analysed, and the following results obtained : — 
