384 THE EOYAL INSTITUTION. [CHAP. VI. 



' A fourth peculiarity, which, however, is less exclu- 

 sively and originally a doctrine of Sir Humphry Davy, 

 is the theory of the simplicity of the proportions in 

 which all bodies combine a theory the explicit 

 illustration and general and minute application of 

 which the science is principally indebted to our 

 countryman Mr. Dalton.' 



How far later discoveries have advanced our know- 

 ledge can be seen in the strange words, as they now 

 sound, which Dr. Young uses when he mentions the 

 first researches of Davy. 



' Certain bodies which attract each other chemically, 

 and combine when their particles have freedom of 

 motion, when brought into contact still preserving 

 their aggregation, exhibit what may be called electrical 

 polarities, and by certain combinations these polarities 

 may be highly exalted ; and in this case they become 

 subservient to chemical decompositions, and, by means 

 of chemical arrangements, the constituent parts of 

 bodies are separated in uniform order and in definite 

 proportions.' 



The review then gives the account of the discovery 

 of potassium, sodium, barium, strontium, magnesium, 

 aluminum, glycinium, zirconium, silicium, and itrium 

 and boron. 



On the subject of oxymuriatic acid gas Dr. Young 

 says ' we cannot help thinking his tone somewhat more 

 decisive than the present state of the investigation alto- 

 gether authorises,' and he strongly objects to Davy's 

 terminology ; which never was adopted by chemists. 



