158 ANNUAL OF SCIENTIFIC DISCOVERY. 



globule solidifies, the congelation of others still fluid may be effected 

 by bringing them in contact with the frozen particle. Different 

 effects are thus produced, depending on the temperature and the size 

 of the spheres. Sometimes the spheres touching solidify suddenly, 

 but remain separate ; sometimes they combine together, the one join- 

 ing on or else enveloping the other at the moment of congelation. 

 Irregular spheres formed of concentric layers and other varied shapes 

 are thus produced. The author traces a resemblance between these 

 frozen particles and the shape and structure of hailstones, which he 

 conceives may be formed by a process somewhat analogous. 



Other substances besides water present the foregoing phenomenon. 

 Thus M. Dufour has experimented with sulphur, phosphorus, and 

 naphthaline. He finds that when melted sulphur is suspended in a 

 solution of chloride of zinc having the same density as itself, the tem- 

 perature may be reduced to 70 or 50 without solidification taking 

 place. In this instance, the liquid condition possesses remarkable 

 stability. When the globules of sulphur remain fluid at 50 or 60 

 below the usual temperature of solidification, their change of state 

 constitutes an interesting object. Globules half a niillim. in diameter 

 sometimes remain liquid at 5 Cent, for several days. Solidification 

 is best provoked by contact with a piece of sulphur. Phosphorus in 

 like manner may be reduced far below 44 Cent, without solidifying, 

 and small globules may even be reduced to 5 or 6. Many other 

 substances would doubtless present the above phenomena. The prin- 

 cipal obstacle lies in the difficulty of finding suitable menstrua. 



Additional Experiments on the Boiling Points of Solutions. The 

 boiling point of water is raised by the addition of a soluble salt, or by 

 the addition of a strong acid, and this augmentation of the boiling 

 temperature depends upon the relative amount of salt or acid added 

 as the case may be ; but hitherto no general formula? have been given 

 to express the relation between the augmentation of boiling tempera- 

 ture and the relative weight of the substance added to the water. 

 Mr. T. Tate has performed a series of experiments, with the view of 

 obtaining some laws on the subject ; and states that he has found, for 

 certain chlorides, nitrates, and carbonates, that the augmentation of 

 boiling temperature may be approximately expressed in a certain 

 power of the percentage of the salt dissolved. 



RADIATION AND ABSORPTION OF HEAT AND LUNAR RADIA- 

 TION. 



In a recent letter to Sir John Herschel, in reference to the re- 

 searches of the latter on solar radiation, Prof. Tyndall states that he 

 has been for some time experimenting on the permeability of our at- 

 mosphere to radiant heat, and that he arrives at the conclusion that 

 true air, i. e., the mixture of oxygen and nitrogen which forms the 

 body of our atmosphere, is, as regards the transmission of heat, a 

 practical vacuum. The results from which the opacity of the air 

 have been inferred are all to be ascribed to diffused extraneous mat- 

 ters, and mainly to aqueous vapors. On Oct. 10, last, he found the 

 absorptive action of the common air in the laboratory of the Royal 

 Institution, London, to be made up of three components, the first 



