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Transactions of the Society. 
I have tried the solubility of phosphorus in phenyl-thiocarbimide, 
hut I find it to be very slight, except while the solvent is hot ; on 
cooling, the greater part of the phosphorus is precipitated again. 
6. Piperine (formula of molecule, 0 17 H 19 "N0 3 ). This, like quini- 
dine, is a substance so strongly imbued with what perhaps I may call 
the “ original sin ” of crystallisability, that until lately I never thought 
it worth examination. 
It is, as its name implies, the alkaloid existing in ordinary pepper, 
from which it may be extracted by alcohol. It occurs in commerce 
as yellowish -white monoclinic prisms, isomorphous with those of 
quinidine, but containing no water of crystallisation. When heated, 
the crystals begin to melt at 135° C., forming a yellowish slightly 
viscous liquid, which solidifies into a light yellow tough transparent 
resinous mass, soft enough to be easily indented with the finger-nail, 
and rather “tacky.” This resin-form of piperine when heated to 
100° C. is converted (like quinidine, but not quite so readily) into a 
white mass of crystals, which on further heating melt at 135° C., 
passing into the resinous condition. If the temperature is raised still 
further, at about 200° the substance begins to decompose, and the 
liquid becomes dark yellow or brown, owing to separation of carbon. 
Eesinous piperine has, unlike quinidine, very strong cohesive 
properties, and does not give the slightest trouble by cracking under 
mechanical stress or thermal changes, even when in thick pieces. I 
find its refractivity to be remarkably high, its index of refraction 
for yellow sodium light being 1 • 681 at 18° ; but its dispersive power 
is more remarkable still, the coefficient of dispersion being no less than 
(/ u H — fi H =) 0*141. I have not yet determined the indices for a 
y . a 
sufficient number of wave-lengths to enable me to state exactly where 
the greatest extension of the spectrum takes place, but it is certainly 
in the part including the shorter waves, corresponding to green and 
blue (as in the case of carbon disulphide). 
It will be seen from the above-mentioned properties that piperine 
would serve admirably for a cement and mounting material, if it were 
not for its suspicion of crystallisability and its abnormal dispersion. 
Both of these defects seem likely to be lessened by admixture with 
other more orderly materials, and the most promising which I have 
tried at present is Canada balsam. A mixture of four parts (by weight) 
of piperine with one part of balsam has a refractive index for yellow 
sodium light of 1 *657 at 16°, and a coefficient of dispersion of 0*130. 
The tendency to pass into the crystalline condition when heated to 
100° seems greatly lessened, though not removed altogether. 
One other point I would notice with regard to piperine (and quini- 
dine also) for the purj)ose of eliciting the experience of others. I am 
inclined to think that the tendency towards crystallisation becomes 
greater wdien the resin-form has been once or twice re-melted. It is 
well known that some kinds of glass, especially the German " soft 
