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220 POPULAR SCIENCE REVIEW. 
made a burner of a bore rather large compared with fits height, and then 
drew in its upper edge into the form of an open-ended thimble, so contracting 
the orifice of escape to about two-thirds the area of the tube, and rendering 
this orifice practically an opening in a thin horizontal wall or plate. The 
results of this modification far surpassed my anticipations. A burner thus 
constructed gives a perfectly nonluminous flame with gas pressures varying 
between 1*5 and 01 inch of water, and with the lowest of these pressures 
cannot be made to retreat by the most violent handling in the way of sudden 
movement or waving about in the air, even when this violence is carried to 
the extent of extinguishing the flame altogether. Under like conditions of 
pressure, a burner of the ordinary construction is made to retreat by a slight 
draught of air, or a very moderate amount of motion.” 
The last Form of French Balloon is thus described in a recent paper 
published in the “ Chemical News,” on the subject of the u development of 
the chemical arts during the last ten years,” by Professor A. W. Hofmann. 
Speaking of aeronautics, he says the last impulse was given, not by festivity, 
but by the terrors of war and the siege of Paris. The Academie des 
Sciences commissioned one of its members, Dupuy de Lome, to make experi- 
ments on steering balloons, and the Government furnished the requisite 
means. Dupuy gave his balloon the fish shape, and, in order to render its 
shape stable in the wind, he fitted it with an internal secondary balloon 
( ballonet ), containing more or less air, and equal in bulk to one-tenth part of 
the maia balloon. The air could be let out of this inner balloon by valves, 
or driven in again by means of a bellows in the car, according to a plan 
which Meusnier had devised as early as 1783 to supersede the use of ballast. 
Dupuy’s balloon was further distinguished by a very firm method of sus- 
pending the car, and by the use of a varnish impermeable to gases, and 
made of gelatin and tannin dissolved in pyroligneous acid. The propelling 
screw was not turned by a steam-engine, but by eight men in the car. The 
balloon, containing 3,450 cubic metres, was filled with hydrogen obtained 
from iron and sulphuric acid, and went up at Vincennes on February 1st, 
1872, carrying fourteen persons. After a flight of two hours, it was let 
down at Noyon, a distance of 106 kilometres. By means of an anemometer, 
Dupuy was able to determine the independent speed of the balloon at 2*82 
metres per second, whilst that of the wind was 16 to 17 metres, and the 
course of the balloon made an angle of 12° with the direction of the wind. 
The problem of steering had, therefore, been solved, though only to a very 
slight degree — sufficient for a calm, but insufficient for overcoming even 
moderate winds. The speed attained was slight. Both conditions of success 
depend on the employment of stronger sources of mechanical power, and this, 
again, requires an increase of its power of ascent, i.e. of its relative levity 
with an enlarged volume. 
Gyratory Movements of Salts in Water. — M. M. H. Lescceur says (‘‘Bull, 
de la' Chimique de Paris ”), that substances possessing the epipolic force 
may be arranged in two classes: — 1. Bodies Insoluble in Water. — When 
once they are spread out all motion is arrested, and the movement of every 
other body is suspended (fixed oils, fatty bodies, &c.). . 2. Soluble or Volatile 
Bodies. — The superficial layer produced instantaneously dissolves, or is 
volatilised. The movement is continuous. The saturation of the liquid and 
