SCIENTIFIC SUMMARY. 
523 
which he tests the oil is to place about a quarter of an ounce into a 
six-ounce stoppered bottle, and, after inserting the stopper, shake the 
bottle well for three or four minutes; upon then removing the stopper, 
a lighted match is held to the mouth of the bottle ; if there was a rush 
of pale blue flame through the bottle, the oil was said to give off an 
explosive vapour, and according to the temperature at which this test 
was performed the oil was said to be dangerous or ordinarily safe. Out 
of thirty-two samples two were found to explode at the temperature of 
60° Fah., and were consequently highly dangerous. This temperature can, 
however, be only considered as the lowest limit of possible danger ; the 
actual limit being a temperature as high as 85° or 90°, which may be cal- 
culated upon as often existing in the cistern of a lamp ; this high tempe- 
rature being produced by long-continued burning in a warm room and on 
a table near the fire. The experiment was, therefore, repeated at this 
temperature with the remaining samples of oil, when three more were 
found to be explosive ; the other oils were then tested at temperatures 
of 100°, 120°, and 150° ; four of them were dangerous at the first, three 
others at the second, and the remaining twenty at the highest temperature. 
This is, however, beyond the limits of actual danger, and these twenty 
may therefore be looked upon as very safe oils. The classification of these 
oils presents several points of interest. They consisted of Young’s 
Paraffin and American oils ; the whole of the former were found to be 
safe, whilst only two American oils were safe, all the others exploding 
at or below 120°. It must, however, be remembered, that whenever the 
oils are scattered upon linen or woollen rags, at even the ordinary tem- 
perature of the air, they burst into violent, flame upon a momentary con- 
tact with a lighted match or candle. This is the most dangerous property 
of mineral oil, and in it there is no considerable difference between Young’s 
best samples of paraffin oil and the worst American oils. Before a fresh 
sample of paraffin oil is purchased for doniestic illumination, it should be 
tested in this way. The proper temperature can be readily communicated 
to the bottle and oil, by immersing it in water at 120°, and no oil which 
gives off an explosive vapour at that temperature should be allowed to enter 
a dwelling-house. The real danger to society consists in the practice of 
selling one species of oil for another ; genuine paraffin oil is perfectly safe 
in a proper lamp ; but the majority of the American substitutions are scarcely 
safe under any circumstances. 
GEOLOGY AND PALAEONTOLOGY. 
O NE of the most noteworthy of modern geological discoveries is a strange 
animal, half reptile, half bird, from the Lithographic slate of Germany. 
Covering a slab of about one foot and a quarter square, the remains indicate 
a creature abundantly feathered. A single feather like those of the common 
partridge, showing the quill and all the fibres of the vane beautifully pre- 
served, had been previously described from the same deposit by Yon Meyer ; 
but this fossil, unlike any bird, has the feathers, which likewise show stem 
and vane, at the extremity of the arm (the hand not being preserved) 
