968 REPORT— 1885. 
decomposes even in a freezing mixture, and instantly on warming yielding hydro- 
bromic acid and a black resin. Nor could any oxidation product be obtained, the 
hydrocarbon being apparently completely burnt on treatment with permanganate 
or chromic acid. Nitric acid dissolves the crystals easily, and the addition of 
water to the solution throws down an amorphous nitro-compound, but the quantity 
obtained was insufficient for analysis. 
In order to attempt to trace the genesis of this solid hydrocarbon, I had recourse 
to my friend Mr. Josiah Hardman, who, through his chemist, my former pupil Mr. 
Irwin, kindly provided me with about 200 litres of the first rannings from 240 tons 
of tar. This product was carefully distilled, and about 2 litres of liquid boiling 
below 30° was collected. Of this 200 c.c. was distilled on April 16, the whole 
boiling below 30°, and leaving no solid residue. On again distilling this portion, 
which had been at once sealed in a tube nearly filled with the liquid, about 60 c.c. 
boiled above 30°, and a solid crystalline residue, weighing about two grams, was 
left behind. This substance melted at 30°, and proved to be the hydrocarbon 
C,,H,,._ One hundred ¢.c. of another portion of the volatile mixed hydrocarbons, 
obtained from a second sample of the first runnings, was distilled on March 7. It 
all came over between 30° and 40°, and no trace of solid crystals was noticeable. 
On April 13 the liquid contained a high-boiling constituent, and the residue yielded 
crystals of ©,,H,,. On repeating the operation on May 5 the thermometer rose to: 
75°, and crystals were again obtained from the residue. The fraction of this last 
portion boiling from 20° to 30° was then sealed up till June 29, when it was again 
distilled, and from it a small quantity of the crystals was obtained. A third por- 
tion of the volatile hydrocarbon from a different tar also exhibited the same be- 
haviour ; when first distilled it all came over below 30°, and gave no indication of 
the presence of the solid hydrocarbon, but after standing in a sealed tube for six 
weeks the thermometer ran up to 65°, and the last drops of distillate yielded the 
crystallised substance. Hence there can be no doubt that these volatile hydro- 
carbons do polymerise spontaneously at the ordinary temperature, and that the 
solid C,,H,, is probably the final product. 
To identify the volatile hydrocarbon or hydrocarbons which yield the solid 
substance proved no easy matter. In order to separate the acetylenes the most 
volatile product obtained was shaken up with an ammoniacal nitrate of silver 
solution. The light-yellow precipitate obtained consisted mainly of the silver, 
composed of ethylacetylene, as its molecular weight was found to be 164°3 and 
158'7 instead of 161. Portions of the mixture of hydrocarbon thus freed from the 
acetylene were distilled on March 4, and the whole distilled over at 30°, and showed 
no trace of crystals. It was then allowed to stand, as described, until April9, 
when the liquid was found to yield the same solid body. Hence it appears that 
hydrocarbons, not acetylenes, are capable of spontaneous polymerisation. For the 
purpose of separation, these non-acetylene hydrocarbons were brominated. The 
fraction boiling below 30° yielded a large crop of a well-crystallisable bromine 
compound which, on analysis, proved tc be butine tetrabromide, C,H,Br,, the 
percentage of bromine obtained being 85°7 and 85:3 as against 85°6 required.! 
Amylene dibromide, boiling at 170°-180°, and giving a percentage of 70:0 of bromine 
as against 69°56, was also obtained in quantity. A liquid pentine tetrabromide, 
C.H,Br,, also occurred amongst the numerous brominated derivatives. This was 
distilled in a vacuum, and yielded, on analysis, 81:83 per cent. of bromine as against 
82°47 per cent. The sp. gr. of this bromide was 2°37. Whether, as seems not 
unlikely, the new crystalline hydrocarbon is derived from a hydrocarbon, C,H,, an 
isomeride of valylene, must at present remain doubtful, as the search for this body 
proved unsuccessful. 
5. On some new Vanadium Compounds.? By J. T. Brrerey. 
These compounds are formed by the following remarkable reaction :—If a blue 
solution of hypovanadic sulphate be mixed with a colourless solution of an alkaline 
’ The melting point of this tetrabromide was 116°; that of Helbing’s was 99° 
(L. Annalen, 172, 281.) 
* Printed in full in the Journal of the Chemical Society, 1885. 
