188 ODOROGRAPHIA. 
crowding out all other small plants. There is a white-flowered 
variety (Petasites alba). It is a smaller plant and the flowers are 
not quite so highly scented as the purple-flowered. 
Artificial Heliotrope. 
Piperonal, Cz;H,O;, commercially known as “ Heliotropine,” 
has a very agreeable odour very much like that of heliotrope. The 
starting-point in its manufacture is Piperine, Cy,7H,O3. Ground 
pepper, preferably the white Smgapore pepper, as it contains the 
largest amount of alkaloid (9°15 per cent.), is mixed with twice 
its weight of slaked lime and a sufficient quantity of water; the 
solution is then evaporated to dryness on a water-bath and the 
powder exhausted with commercial ether, from which the piperme 
can be obtained nearly pure on evaporation, in large crystals of a 
faint straw-yellow colour. To obtain it perfectly pure, it must be 
dissolved in alcohol and re-crystallized. Another process of pre- 
paring piperine is to exhaust the pepper with alcohol of sp. gr. 
0°833 and distil the tincture to the consistence of an extract. 
This extract is to be mixed with potash-lye, which dissolves the 
resin and leaves a green powder; by washing this in water, dis- 
solving in alcohol, crystallizing and re-crystallizing, it is obtamed 
colourless *. 
Piperine is converted into potassium piperate by boiling it for 
24 hours with its own weight of caustic potash and from 5 to 6 
parts of alcohol in a large retort, using an inverted Liebig’s con- 
denser. On cooling, the potassium piperate crystallizes out im 
shining yellow lamin. It is washed with cold alcohol and re-erys- 
tallized from hot water. If coloured, it is bleached by animal 
charcoal. As thus obtained, it is in nearly colourless crystals, 
which become yellow under the influence of light. 
One part of potassium piperate is dissolved in from 40 to 50 parts 
of hot water, and a solution of 2 parts of potassium permanganate 1s 
gradually poured into the hot liquid with constant stirrmg. Each 
drop of the latter is almost instantly dissolved, and the solution 
acquires a very pleasant odour. A pasty mass of brown manganic 
hydrate separates, which is placed on a filter and washed with hot 
water until the washings cease to smell of heliotropine. These 
* Poutet, Journ. de Chim. Med. i. p. 5381. 
