280 ON ALOINE, THE CATHARTIC PRINCIPLE OF THE ALOES. 
a pale yellow colour, which does not change when they are 
dried in the air, they may be regarded as pure aloine. 
Aloine is quite neutral to test-paper. Its taste is at first 
sweetish, but soon becomes intensely bitter. Aloine is not 
very soluble either in cold water or in cold spirits of wine ; 
but if the water or the spirits of wine are even slightly warmed, 
the solubility of the aloine is exceedingly increased : the 
colour of these solutions is pale yellow. Aloine is also very 
readily dissolved by the carbonated and caustic fixed alkalies 
in the cold, forming a deep orange- yellow solution, which 
rapidly grows darker, owing to the oxidation which ensues. 
The effects of ammonia and its carbonate are precisely similar. 
When aloine is boiled either with alkalies or strong acids, it 
is rapidly changed into dark brown resins. A solution of 
bleaching-powder likewise gives aloine a deep orange colour, 
which soon changes to dark brown. Aloine produces no 
precipitate in solutions either of corrosive sublimate, nitrate of 
silver, or neutral acetate of lead. It also yields no precipitate 
with a dilute solution of subacetate of lead; but in a concen- 
trated solution it throws down a deep yellow precipitate, which 
is pretty soluble in cold water, and is therefore difficult to wash. 
This precipitate is by no means very stable ; and when it is ex- 
posed even for a short time to the air, it becomes brown. 
When powdered aloine is thrown, in small quantities at a 
time, into cold fuming nitric acid, it dissolves without evolving 
any nitrious fumes, and forms a brownish-red solution. On 
adding a large quantity of sulphuric acid, a yellow precipitate 
falls, which, when it is washed with water to remove all ad' 
hering acid and then dried, explodes when it is heated. It 
plainly, therefore, contains combined nitric acid. I could not, 
however, succeed in obtaining this compound in a crystalline 
state, as when it was dissolved in spirits it appeared to be 
decomposed. When aloine is digested for some time with 
strong nitric acid, much nitrous gas is evolved, and it is con- 
verted into chrysammic acid, but without the formation of any 
nitropicric acid, as is always the case when crude aloes is sub- 
jected to a simiW treatment. A quantity of aloine was boiled 
with a mixture of chlorate of potash and muriatic acid. The 
acid solution was evaporated to dryness, and digested with 
strong spirits of wine. The greater portion of the spirits was 
removed by distillation ; and the remainder, when left to spon- 
taneous evaporation, yielded a syrup which could not be made 
to crystallize. Not a trace of chloranil was produced. 
When aloine is destructively distilled, it yields a volatile oil 
of a somewhat aromatic odour, and also a good deal of resinous 
