SCIENTIFIC SUMMAKY. 
319 
are employed. Persulphuric acid prepared in this manner is not a perma- 
nently stable body. The beautiful crystalline needles begin to crumble 
away in a few days, and are soon converted into a snow-like mass, which 
appears to be a compound of sulphuric acid and persulphuric acid. The 
same substance is formed when the discharge is first transmitted, and appears 
consequently to be an intermediate product. 
Fluoranthene. — This is a new hydrocarbon obtained by Fittig and Geb- 
hard from coal tar (“Ber. deutsch. chem. Gesell. Berlin” x. 2141). In pre- 
paring and purifying a large quantity of pyrene, a substance was discovered 
having the formula O 15 H 10 , fusing at 100° and crystallizing in large lustrous 
plates. This is the new body. When treated with the requisite reagents it 
yielded the picric acid compound C 15 H 10 + C 6 H 3 (N0 2 ) 3 0 and the trinitro- 
derivative C 15 H 7 (N0 2 ) 3 . When oxidized with chromic acid solution it, 
like phenanthrene, evolves carbonic acid and is converted into a mixture of 
a chinone and an acid having the formula C 14 II 8 0 3 ; the barium salt of this 
body crystallizes in little warty concretions and the calcium salt in small 
golden-yellow needles. It is isomeric with oxyanthrachinone, but has the 
same empirical formula only as that body. It is undoubtedly an acid, 
containing beyond all question the group COOH. When distilled with 
finely divided zinc it yields nearly the theoretical amount of fluorene, and 
when heated with lime splits up into carbonic acid and diphenylenketone, 
which has led the authors to give it the name of diphenylenketon carbonic 
acid. Fittig believes the idryl of Goldschmiedt to be identical with fluoran- 
thene. 
The Reaction of Nitrogen and Water. — Berthelot, having had occasion to 
repeat the experiments on the formation of ammonium nitrite by means of 
the electric discharge, now finds that absolutely pure nitrogen when exposed 
in the concentric tubes, in contact with water, to the discharge of a powerful 
Buhmkorff apparatus for from eight to ten hours yields ammonium nitrite 
beyond all question. The salt does not appear to be formed unless the dis- 
charge is a powerful one. With currents of low tension nitric acid is not 
formed in moist air. The formation of nitrates and nitrites in atmospheric 
air is assumed therefore to be due to the action of lightning (“ Ann. Chem. 
Phys.” [5], xii. 445). It must not, however, be forgotten that Zoller and 
Grete have reopened the inquiry whether ammonium nitrite is a product of 
the combustion of hydrogen in air, and the result of the experiments, con- 
ducted under most rigorous conditions, goes to show that during the com- 
bustion of absolutely pure hydrogen in perfectly pure air, small but distinct 
quantities of the nitrite are formed. (“ Ber. deut. chem. Gesell. Berlin.” x. 
2144.) 
GEOLOGY AND PALAEONTOLOGY. 
The Date of the Last Glacial Epoch. — Mr. N. H. Winchell has communi- 
cated a paper to the Geological Society in which he endeavours to determine 
the date of the final cessation of glacial conditions in North America by 
determining the rate of recession of the Falls of St. Anthony, which are 
situated near the junction of the Minnesota and the Mississippi. These 
