532 Royal Society : — 



The rise of heated air in a chimuey, sometimes pointed at as an illus- 

 tration, was shown to be not analogous to that which takes place 

 when the sun heats the air unequally in different latitudes ; if it 

 were, the theory of Halley would be true, and cool air would flow 

 from all parts around to the greatly heated locality, just as cool air 

 passes to a fire, and, when heated, up a chimney. It was then shown 

 that it is gravitation which establishes an equilibrium of pressure in 

 the atmosphere, and that direct solar heating of the surface of the 

 earth and the air near to it, does not destroy that equilibrium. The 

 sun by heating the gases merely expands them, in proportion to the 

 increase of temperature in the part near the surface ; and the gases 

 over every portion of the hemisphere that is exposed to the action of 

 the sun are proportionally heated, expanded and raised without any 

 overflow of air taking place, leaving the equilibrium of pressure un- 

 disturbed by such heating. The solar heat merely raises the air that 

 is near the surface, over the most heated latitudes, a little higher than 

 the adjoining less heated, the difference in the rise in the various 

 latitudes, from the polar to the tropical regions, being successively 

 small ; and as there is no alteration produced in the weight of any 

 vertical column of the atmosphere, in any latitude, there is neither 

 overflow of air above, nor disturbance of the equilibrium of pressure. 

 The great disturbances that take place in the atmosphere were then 

 maintained to be caused by the heat which is conveyed, from the 

 surface of the globe, in vapour to different parts of the atmosphere 

 at various heights, and liberated in those parts when the vapour is 

 condensed into liquid. This liberation of heat creates ascending cur- 

 rents in the parts locally affected, when horizontal winds, produced 

 by gravitation, blow over the surface towards the ascending currents 

 to re-estabhsh the disturbed equilibrium. This process, by heating 

 the air in the middle regions, was asserted to have been proved to be 

 the cause, not only of the great trade-winds and the monsoons, but 

 of the storms and local winds over the different regions of the globe. 



*' Notes of Researches on the Poly-Ammonias." By A. W. Hof- 

 mann, LL.D., F.R.S. — No. II. Action of Chloroform upon Aniline. 



In a former Note I have alluded to some new alkaloids which are 

 produced by the action of the bromides of triatomic alcohols upon 

 the primary amidogen bases. 



I have since examined more minutely one of these bodies. At the 

 common temperature, chloroform and aniline may be left in contact 

 for a considerable time without any change becoming perceptible. 

 Even at the temperature of boiling water scarcely anj reaction takes 

 place. But on exposing for ten or twelve hours a mixture of about 

 equal volumes of chloroform and aniline in sealed tubes to a tem- 

 perature of 180° or 190° C, a hard brown crystalline mass is ob- 

 tained, which consists chiefly of the hydrochlorates of aniline and of 

 a new crystalline base. 



To obtain this compound in a state of purity, the brown crystalline 

 mixture formed in the digester-tubes is triturated with a small quan- 

 tity of water, thrown upon a filter and washed with water. The first 



