pa a 
’ 
Sxey.—On the Poisonous Principle of Brachyglottis _ 401 
The residue in the retort, however, also gave the same reaction, although 
the distillation had been continued for eight hours; nor did it appear pos- 
sible to eliminate from this residue the substance which is colourable in this 
way. To ascertain, therefore, whether or not this colourable substance is 
wholly volatile, I evaporated an ethereal solution of the balsam to dryness, 
and the thin film so obtained I submitted to a temperature of 212° Fahr. for 
two hours. The residue was not found capable of colouration by acids. 
It was established, therefore, that the only part of the balsam which gives 
this chromatic effect is volatile, and as I was not able to separate any solid 
matter from this distillate I conclude that it is an essential oil. This oil 
is, I find, so rapidly changed in contact with air and water at an elevated 
temperature, that it is best separated from the balsam by dry distillation, 
out of contact with air as far as possible. 
Separated in this way, its taste and other properties are besides best 
observed. It is then found to be slightly bitter and acid, warm to the 
mouth, with a fragrant odour ; it is feebly soluble in water, readily soluble 
in alcohol, also in ether. An aqueous solution of it affords no precipitate 
with mercuro-iodide of potassium, nor yet with mercuric-chloride, but it 
gives a pale-yellow or white precipitate with the above-named salts succes- 
sively applied. It also gives a precipitate with tannic acid, but none with 
alkalies, acids, or bi-chloride of platinum. , 
With oxalic or tartaric acid, even at a temperature of 212° F., it does 
not colour; but with all the mineral acids, or even acetic acid, it colours 
as has been already indicated, and this even at common temperatures. If 
the oil is, however, first warmed with any free alkali, it then does not 
become coloured by contact with any acid. 
The blue or light purple compound formed out of this oil by acids,* 
assumes a yellowish colour when alkalized, but reacquires its normal tint 
When acidified. In contact with warm nitric acid or nascent hydrogen it 
also loses its blue colour, and in such a way that it appears impossible to 
restore it. , 
It has been found to be almost unalterable under ordinary conditions, 
Standing as it does with seeming impunity a temperature of 212° F., but 
Whether it has sufficient permanency to allow of being profitably used in 
the dye-house, has yet to be ascertained. sa 
The nature of the change which is wrought upon the oil in question ; 
while it is acquiring the colour described, I cannot as yet ascertain. AllI 
an yet be certain of is that it then splits into two or more substances. ia 
this respect it resembles digitaline, that poisonous resin of foxglove which — 
* Both the halaam sod ibis BE . iy duct of it were exhibited. 
