386 Prof. Curistison on the Poisonous Properties of Hemlock, 
tilled anew, it is simply reproduced without any material change 
except some loss of strength. But if it be previously neutralized 
with an acid, such as the sulphuric, the volatile poisonous prin- 
ciple becomes fixed, and water alone is distilled over. The resi- 
duum consists of sulphate of conia, sulphate of ammonia, and 
resinoid matter, the resin and ammonia being produced by de- 
composition of a part of the conia under the operation of heat 
and the access of air. In order to obtain the conia, the mass is 
subjected to a mixture of two parts of rectified spirit and one of 
sulphuric ether, which leaves the sulphate of ammonia undissolv- 
ed. And then, the ether and alcohol being distilled carefully off, 
the remaining sulphate of conia is heated gently with a little wa- 
ter and caustic potassa ; upon which there is obtained in the re- 
ceiver a watery solution of conia in the lower part, and floating 
on this a layer of nearly pure conia, colourless, transparent, and 
presenting the physical appearance of an oil. 
In this state the conia contains a little ammonia and a fourth 
of its weight of water, the latter of which may be removed by 
chloride of calcium, and the former by exposing it to the air- 
pump vacuum so long as bubbles of gas escape. By neither pro- 
cess of purification, however, is the physical appearance of the 
conia materially changed. 
Conia thus obtained has the appearance of a colour.ess vola- 
tile oil. It is lighter than water, of a very powerful diffusible 
repulsive odour, somewhat like that of hemlock itself; and intense- 
ly acrid to the taste. It has a strong alkaline action on reddened 
litmus or turmeric. It is readily soluble in diluted acids, which 
it neutralizes ; but its salts have not yet been obtained in the 
erystalline form. It is sparingly soluble in water, to which it 
imparts its odour and taste. It also combines with about a 
fourth of its weight of water to form a hydrate of conia. Both 
this hydrate and the watery solution possess the property of be- 
coming opaque when slightly heated, and recovering their trans- 
parency on being again cooled. When exposed to the air it 
