190 Extracts from Berzelius^s Annual Report for 1843. 



. Atomic Weight of Cerium and Lantanium. — M. Beringer (Ann. der 

 Chem. und Pharm. XLII, 139) has determined the atomic weight of 

 cerium and found it to be 576-97. M. Rammelsberg (Pogg. Ann.LV, 

 64) has found for lantanium 554-88, and for cerium 572-8. 



Variation of the Boiling Point of Water in Vessels of Different 

 Materials. — M. Marcet (Ann. de Chim. et de Phys. V, 449) has made 

 a series of accurate experiments upon the variations of the boiling point 

 of water, dependent upon the nature of the vessel in which it is made 

 to boil. The following are the results of his researches : — 1st. The 

 boiling point of water in glass vessels is from 100° -3 to 102° cent., va- 

 rying with certain circumstances, more especially with the different 

 kinds of glass. In these cases the temperature of the vapor of water 

 is constantly the same, and some hundredths of a degree lower than 

 when water is boiled in metallic vessels. 2d. Whatever the nature of 

 the vessel in which the ebullition takes place, the temperature of the 

 vapor is always lower than that of the water from which it is genera- 

 ted. This difference in the case of glass vessels is about l o, 06 cent.; 

 in metallic vessels 0°-15 to 0°-20 cent. There is only one exception to 

 this rule, which is when the interior of the vessel, whether of glass or 

 metal, is covered with a thin coat of sulphur or gum lac, or any other 

 substance which exercises a repulsion for water; the boiling water and 

 the vapor then have the same temperature. 3d. Contrary to the opin- 

 ion generally admitted, it is not in metallic vessels that the boiling point 

 is lowest under an increased pressure, but in glass vessels covered in- 

 ternally with a thin coat of the substances mentioned above. 4th. in 

 glass vessels having the internal surface perfectly smooth and free from 

 foreign matter, water and alcohol can be heated several degrees above 

 their boiling point before they enter into ebullition. Water can be thus 

 heated to 105° cent. If the experiment does not succeed, it is because 

 there is foreign matter adhering to the glass. The experiment may e 



In 



performed successfully with a new vessel, by first heating sulphuric 

 in it to 150° cent., then washing it out with pure water. 



Evaporation of Water under Electrical Insulation. — M. R°* 

 (Phil. Mag. XX, 45) suspended two similar capsules of eight and a W* 

 inches diameter by silk strings, over a stove that was heated daily- 

 each vessel eight and a half ounces of water was poured. One o 

 vessels communicated with the earth by a copper wire. At the en 

 twenty-four hours, 2 ounces and 279 grains had evaporated from 

 insulated capsule, and 3 ounces and 144 grains from the other, making 

 a difference of 345 grains in favor of the capsule in communicate 

 with the earth. The same result was obtained with the heat of the su . 



The Action of Light upon an Iodized Silver Plate, generates a ^ 

 rent of Electricity.— M. Becqueral (Pogg. Ann. LV, 588) has sho 





