PHYSICS. 229 



at which a liquid boils is the temperature at which its ten- 

 sion equals the pressure of the atmosphere. The apparatus 

 consists of a thin U tube ofsrlass about a decimeter Ions: and 

 1.2 centimeters diameter, one leg being closed and the other 

 open, and both graduated into millimeters. Upon filling the 

 closed end of the tube with mercury, introducing a drop of 

 the liquid at that end, and placing the apparatus in a suit- 

 able bath, the temperature at which the level of the mercury 

 is the same in both branches is the boiling-point of the 

 liquid. An apparatus for introducing the liquid is also de- 

 scribed. Essentially the same apparatus was described by 

 Jones in a communication to the Chemical Society of Lon- 

 don, and by Main in the Chemical News. 



Carnelley, having determined by careful calorimetrical ex- 

 periments the fusing-points of various salts, has, in conjunc- 

 tion with Williams, made use of the data thus obtained for 

 the purpose of determining the boiling-points of substances 

 which are beyond the range of ordinary thermometers. 

 Fragments of two or three salts are placed in the vapor or 

 liquid and examined to see if they melt. Thus, for example, 

 while sodium chlorate melts in the vapor of mercuric chlo- 

 ride, sodium nitrate does not. Anthracene vapor melts po- 

 tassium nitrate, but not the chlorate. Its boiling-point is be- 

 tween 339 and 359. The authors hope to fix in this way 

 the boiling-points of potassium, sodium, etc. 



Vincent has made a careful study of the use of methyl 

 chloride in the production of cold. At ordinary tempera- 

 tures and pressures it is a colorless gas, having a sweet taste, 

 and an odor recalling that of chloroform. At a tension of 

 3.13 meters of mercury at 15 it condenses to a colorless 

 liquid, which boils at 20. It is prepared commercially 

 from vinasse, which is the residue after the fermentation 

 and distillation of beet-root molasses, by calcination for the 

 preparation of potash salts. During the process there is dis- 

 engaged a considerable quantity of trimethylamine, the hy- 

 drochlorate of which decomposes, when heated to 295, into 

 free trimethylamine, monomethylamine, hydrochlorate, and 

 methyl chloride. The gaseous mixture being passed through 

 an acid, the alkaline bodies are removed, and the methyl 

 chloride is left pure for condensation. On exposure of the 

 liquid to the air, it at once boils for an instant, until the tern- 



