396 Intelligence and Miscellaneous Articles. 



from a syrupy consistence almost to the state of solid, this difference 

 is scarcely 1°. 



In order to confirm the part which we have ascribed to the ether 

 we have made experiments with the following solvents. We have 

 obtained the following results : — 



Temperature 

 observed. 



Chloride of methyle -82° 



Sulphurous acid —82 



Acetate of amyle — 78 



Terchloride of phosphorus . . — 76 



Bisulphide of carbon. ....... — 74 



Absolute alcohol —72 



Chloride of ethylene — 60 



With the last three liquids, and especially with chloride of ethy- 

 lene, the solubility of carbonic snow is manifestly less than the 

 others. These also are the liquids which produce least cooling. 



By producing a vacuum over these liquids we can, as Faraday has 

 shown, materially reduce the temperature, even below — 100°. 

 With chloride of methyle and sulphurous acid it happens that this 

 temperature in a vacuum is sufficiently low to solidify the solvent. 

 All the mass then becomes solid, and from this point the tempera- 

 ture remains almost stationary. 



The lowest temperature we have obtained under these conditions 

 is with chloride of methyle. Solidification only takes place at 

 about -106°. 



With chloroform, whose freezing-point is below that of carbonic 

 acid, the action of the vacuum is not needed to produce this effect. 

 Carbonic snow gradually added to the liquid dissolves at first with 

 disengagement of carbonic acid. When the temperature has sunk 

 to —77° this ebullition ceases suddenly, and the whole mass 

 solidifies. There is thus a freezing mixture which congeals under 

 the influence of its own cooling. — Journal cle Physique, September 

 1888. 



A SIMPLE PENDULUM EXPEEIMENT TO EXPLAIN EESONANCE AND 

 ABSOKPTION. BY W. HOLTZ. 



A caoutchouc tube is stretched between two door-posts by 

 means of packthread attached to the ends, and nails. If two 

 string pendulums are hung over this by means of hooks equidistant 

 from the ends at about -J- of the width of the door, and if an impulse 

 be given to one, the other is set in oscillations which increase as the 

 others slacken. When the original one has come to rest the phe- 

 nomenon is inverted. If the pendulums are unequal the second 

 begins to vibrate indeed, but the vibrations do not continuously 

 increase. — Beibl'dtter der Physik, No. 7, 1888. 



