ATOMIC WEIGHTS 



265 



being taken to avoid any loss by splashing or fuming which might result 

 from the violence of the action. To the solution thus obtained the silver 

 solution was added, the silver being something less than a decigramme 

 in deficiency. The remaining amount of silver needed to complete the 

 precipitation of the bromine was added from a burette, in the form of a 

 standard solution containing one milligramme of metal to each cubic 

 centimetre. The final results were as follows, the figures in the third 

 column representing the quantities of bromide proportional to 100 parts 

 of silver. Series A is from the first portion of the last distillate of AlBrg ; 

 series B from the second portion, and series C from the third portion : 



Mean, 82.455, ± .001 



Hence Al = 27.098. 



The experiments to determine the amount of hydrogen evolved by the 

 action of caustic soda upon metallic aluminum were conducted with pure 

 metal, specially prepared, and wath caustic soda made from sodium. 

 The soda solution was so strong as to scarcely lose a perceptible amount 

 of water by the passage through it of a dry gas at ordinary temperature. 

 As the details of the experiments are somewhat complex, the original 

 memoir must be consulted for them. The following results were obtained, 

 the weight of the hydrogen being calculated from tlie volume, reckoned 

 at .089872 gramme per litre. 



