§ 278.] 
PHOSPHORUS. 
227 
. XIII.—Phosphorus. 
§ 278. Phosphorus.— Atomic weight 31 ; specific gravity 1-82 to 
1-84. Phosphorus melts at from 44-4° to 44*5° to a pale yellow oily 
fluid. The boiling-point is about 290°. 
The phosphorus of commerce is usually preserved under water in 
the form of waxy, semi-transparent sticks ; if exposed to the air white 
fumes are given off, luminous in the dark, with a peculiar onion-like 
odour. On heating phosphorus it readily inflames, burning with a very 
white flame. 
At 0° phosphorus is brittle ; the same quality may be imparted to 
it by a mere trace of sulphur. Phosphorus may be obtained in dodeca¬ 
hedral crystals by slowly cooling large melted masses. It may also be 
obtained crystalline by evaporating a solution in bisulphide of carbon, or 
hot naphtha in a current of carbon dioxide. It is but little soluble in 
water. Julius Hartmann 1 found in some experiments that 100 grms. 
of water digested with phosphorus for sixty-four hours at 38-5° dissolved 
•000127 grm. He also investigated the solvent action of bile, and 
found that 100 grms. of bile under the same conditions dissolved 
•02424 grm., and that the solubility of phosphorus rose both in water 
and bile when the temperature was increased. Phosphorus is somewhat 
soluble in alcohol and ether, and also, to some extent, in fatty and 
ethereal oils ; but the best solvent is carbon disulphide. 
The following is the order of solubility in certain menstrua, the 
figures representing the number of parts by weight of the solvent re¬ 
quired to dissolve one part of phosphorus :— 
Carbon disulphide . .... 0-5 
Almond oil ..... 100 
Concentrated acetic acid 2 ... .100 
Ether ......... 80 
Alcohol, specific gravity -822 ..... 400 
Glycerin ......... 588 
Phosphorus exists in, or can be converted into, several allotropic 
modifications, of which the red or amorphous phosphorus is the most 
important. This is effected by heating it for some time, in the absence 
of air, from 230° to 235°. It is not poisonous. 3 Commercial red 
phosphorus does, however, contain very small quantities of unchanged 
or ordinary phosphorus—according to Fresenius, from -6 per cent, down¬ 
wards ; it also contains phosphorous acid, and about 4-6 per cent, of 
other impurities, among which is graphite, 4 and often arsenic. 
1 Zur acuten Phosphor-V erg if tang, JDorpat, 1866. 
2 Phosphorus is very little soluble in cold acetic acid, and the solubility given 
is only correct when the boiling acid acts for some time on the phosphorus. 
3 A hound took 200 grms. of red phosphorus in twelve days and remained 
healthy.—Sonnenschein. 4 Schrotter, Chern. News, xxxvi. 108. 
