SCIENTIFIC SUMMARY. 
207 
oily products, removed from this insoluble portion by alcohol, and subse- 
quently precipitated by the addition of water. The hydrocarbons of the 
marsh gas series retained by the sulphuric acid were removed by decanta- 
tion, washed with water, and dried with fused potash, and, subsequently, 
with sodium. When submitted to fractional distillation it was found that the 
first portion passed over at 155° 0, then the temperature soon rose to 160°, 
remaining at that point for some time. The portions which distilled between 
160° and 170°, between 175° and 190°, and during successive intervals of 20° 
up to 300° were collected separately. These quantities were further purified 
by subsequent distillation and eventually seven products were obtained, each 
of which appeared to have a nearly constant boiling point. These are all 
substances which are known and appear to be identical with bodies which 
have been isolated by Pelouze and Oahours from petroleum. They form the 
highest known members of the marsh gas series, which are characterized by 
their insolubility in fuming sulphuric acid, and by their behaviour with chlo- 
rine and bromine. The first distillate is dekane, C 20 R 22 , probably identical 
with diamyl ; it boils between 155° and 160°, has a vapour density = 5T32 
(calculated = 5-001), and a specific gravity = 0’76 at 15°; bromine water is 
without action on this substance ; bromine, on the other hand, attacks it 
vigorously, as also does chlorine, forming substitution products. The next 
body, undekane, C 22 H 24 , boils at 178°-180° ; it is a colourless very mobile 
liquid having a vapour density = 5*521 and a specific gravity = 0-769 ; sul- 
phuric acid does not act upon it ; with bromine and chlorine, however, it forms 
substitution products. The next four are : duodekane, C 24 H 26 , which boils 
at 195°-198°, has a specific gravity = 0*782, and is acted upon by bromine 
and chlorine ; tridekane, C 26 H 28 , boiling at 215°-220°, having a specific 
gravity = 0*793 ; tetradekane, C 28 H 30 , with a boiling point of 234° to 238°, 
and a specific gravity = 0*812 ; and pentadekane, 0 30 H 32 , which boils at 
.25 8° and has a density = 0*83. The last distillate is hexadekane, C 32 H 34 , 
boiling at 276°-280° ; its specific gravity is 0*85. This body is attacked by 
fuming nitric acid, but no crystalline product was obtained. Many of the 
hydrocarbons, then, which are formed by the action of dilute acid on cast iron 
are identical with natural products contained in the complex material which 
we call petroleum ( Compt . rend., lxxxv. 1003). We are reminded here of 
Mendelej elf’s views respecting the origin of mineral oils communicated last 
year to the Russian Chemical Society (see note in the te Pop. Sci. Rev.,” 
July 1877, p. 317), and of the occurrence at Ovifak, Disko Island, Greenland, 
of vast metallic masses, possibly meteoric, possibly erupted, which contain 
much carbide of iron. 
Persulphuric Acid. — Berthelot has prepared a new acid of sulphur ( acide 
persulphurique) , corresponding in composition with perchloric and perman- 
ganic acid, by the discharge of electricity of high tension, though a perfectly 
dry mixture of equal volumes of sulphurous acid and oxygen ; sulphuric acid 
combines neither with oxygen nor with ozone under similar conditions. The 
electrolysis of concentrated sulphuric acid also yields the new acid in a state 
of solution. It can, moreover, be prepared in a state of solution by cautiously 
mixing a solution of hydrogen peroxide with sulphuric acid, concentrated or 
diluted with not more than one equivalent of water ; when two equivalents 
are present no reaction takes place. In the last-mentioned case the reaction 
