6T0KBS.] HIGHER CHL0R0N1TRIDEP. 129 
motes polymerization. The time required for polymerization varies 
greatly; pure triphosphonitrilic chloride may require two hours or 
more. With the above mixture the time is less, and is shorter the 
higher the boiling point; it is shortened by adding already gelatinized 
substance, which causes the liquid to thicken, and may then be but a 
few minutes; it is also shortened by heating under pressure. Sooner 
or later the liquid begins to thicken, and finally it is converted into a 
stiff, transparent mass, with little or no liquid, and generally discolored 
by traces of organic matter. The tube is then connected with a long- 
necked receiver, exhausted, and the depolymerization and distillation 
effected by heating, from the front backward, to incipient redness. 
This part of the operation proceeds rapidly, as it is only necessary to 
guard against frothing over, and to insure complete condensation, the 
latter being easily effected by having the limb of the tube at least 20 
centimeters long. One hundred grams can be worked up at one time 
and the tube can be used repeatedly The residue does not weigh more 
than a few milligrams. The distillation may also be made at atmos- 
pheric pressure, but the yield of higher products is thereby diminished. 
The distillate, which entirely resembles that first obtained, excepting 
in containing no phosphorus pentachloride and no P 6 N 7 C1 9 , is distilled 
as before, the washing being omitted. In this way the whole quantity 
of material can finally be converted into a mixture of members higher 
than P 4 N 4 C1 8 . 
The united residues boiling above 200° are now submitted to sys- 
tematic fractional distillation at 13-15 millimeters, using an Anschutz 
flask, provided with a '-trap," to prevent flowing back. During the 
first distillation polymerization generally begins when the temperature 
of the bath has reached 270°, but with later distillations at a higher 
temperature, and the higher the purer the fractions are. When poly- 
merization begins, which is indicated by frothing an»d thickening, the 
operation is interrupted and the residue heated in the flask witli water 
in the water bath until it has completely liquefied, which is assisted 
by agitation, the oil separated, 1 and the distillation continued. It has 
not been found practicable to continue the distillation at a higher tem- 
perature than that obtained by heating the bath to 370°, for the liquid 
begins to polymerize in a few moments, and but an inconsiderable dis- 
tillate can be obtained. Moreover, at this temperature the polymer 
mows signs of breaking down into simpler bodies, and the distillate 
loes not consist only of high-boiling members. The total amount of 
inal residue is not very great, and, as shown below, consists likewise of 
)hosphonitrilic chlorides of still higher molecular weight. In later 
listillations from _J0()° upward, polymerization usually stops the proc- 
ss at 260°-270°, but after appropriate washing the residue may be 
In this case a separately funnel may bo used,, as tbe mixture of higher chloronitrides is liquid 
|1 jlow 80°. 
Bull. 167 9 
