128 CONTRIBUTIONS TO CHEMISTRY AND MINERALOGY. [bull. 167. 
heated much above 200°, the liquid frequently separates into two 
layers. The crystals are soluble in gasoline, but the bulk of the prod- 
uct remains as an immiscible oil. 
The neck of the tube is now bent down, the tube placed in an inclined 
combustion furnace, and by cautious heating, finally to incipient red- 
ness, the contents are distilled out. There remains in the tube a very 
voluminous, spongy, black residue of inconsiderable weight, due to 
unavoidable impurities and to the impossibility of causing complete 
reaction in the sense of the above equation. The distillate consists of 
a crystalline mass impregnated with a yellow oil, and contains about 
95 per cent of the theoretical amount of phosphonitrilic chlorides, with 
some phosphorus pentachloride, the chloronitride P 6 N 7 C1 9 , and other 
substances of unknown nature. Before proceeding further, it is neces- 
sary to remove the pentachloride, and for this purpose the distillate 
is melted, poured into cold water, and the flask heated in the water- 
bath for about two hours, the liquids being mixed by blowing air 
through them. The chloronitrides are then allowed to clear under the 
hot water, and forced out by means of a wash-bottle arrangement; a 
separatory funnel can not be used, as the substance solidifies in the 
neck, and if allowed to solidify under the wash water it absorbs so 
much of this as to cause annoyance in the subsequent distillation. 
Special drying before distilling is unnecessary. 
The product is then distilled up to 200° at 13-15 millimeters, using an 
Anschiitz flask, as the distillate solidifies instantly on cooling. The 
residue, containing the members P 5 N 5 Ol 10 up, is set aside for later sys- 
tematic fractional distillation. 1 The distillate, about 70 per cent, con- 
sists essentially of P 3 N 3 C1 6 and P 4 N 4 C1 8 , which, if desired, may be easily 
separated by fractional distillation in vacuo, followed by crystallization 
from benzene. This is more convenient than the method of separating 
by steam. If it is desired to convert it into the higher members, it is 
placed in a combustion tube bent down at about 20 centimeters from the 
open end, and which it should not fill more than one-half after melting. 
This is laid in an inclined combustion furnace and heated to gentle 
boiling of the contents. It is well to heat the tube somewhat strongly 
at a short distance above the liquid, as superheating the vapor pro- 
1 This residue contains the small amount of P G N 7 C1 9 formed as a secondary product of the original 
reagents, and as this is apt to cause inconvenience at a later stage by accumulating with the P 6 N" G Cli 2 , 
it is perhaps well to remove as much as possible at this point. For this purpose the residue is 
allowed to stand for a day or two at the room temperature, and the crystals removed by sucking out 
under a good vacuum, best in a large Gooch crucible. The filtrate is cooled for a day or two in a 
refrigerator, and the new crop of crystals separated in the same way, the filtering flask being allowed 
to stand in the icebox. The oily filtrate is set aside, and the united crystalline products distilled 
up to 240° at 13 millimeters, whereby most of the P 6 N 5 C1 10 passes over. The residue, consisting of 
P 6 N 6 Cli 2 , the small amount of P 6 N 7 Cl9, and the adhering oil, is allowed to crystallize in the refrigerator, 
and the viscous mass is extracted several times with small amounts of gasoline (boiling at 50 3 -80°). 
The residue is boiled with benzene, which extracts the P 6 N 7 C1 9 , which crystallizes on concentrating 
and cooling. The portion dissolved by the gasoline is worked up with the other residues. 
This is the method actually employed, but T am not entirely convinced of its necessity, as it is not 
possible to remove all the P 6 N 7 C1 9 in this way. 
