The Experiments of Ramsay 



able. In his recent researches Ramsay worked 

 with tiny Geissler tubes containing four cubic 

 millimetres of gas, and could reveal traces of 

 elements whose total weight did certainly not 

 exceed one ten thousandth of a milligramme. 



The systematic study of reactions, while 

 supplying the means of characterising chemical 

 species, enables them to be classified in two 

 groups: bodies which can be obtained by syn- 

 thetic reactions, or which can be separated into 

 several others by analytical reactions, are called 

 compound bodies ; and bodies which so far have re- 

 sisted all effort to split them are considered for 

 the present simple bodies or elements. This con- 

 clusion, justified by thousands of experiments, is 

 however only provisional, and it is advisable al- 

 ways to remember the weighty words of Lavoisier : 



"If we attach to the name of elements or 

 principles the idea of the final term attainable 

 by analysis, all the substances which we have 

 hitherto been unable to decompose by any means 

 are for us elements; not because we can be sure 

 that these bodies, which we consider simple, 

 are not actually composed of two or even more 

 principles, but because these principles never 



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