DESCRIPTIVE NOMENCLATURE. 251 



Isatine, Chlorindine, 



Bromisatine, Chlorindoptene, 



Bidromisatine ; Chlorindatmit ; 



Chlorisatine, Chloranile, 



Bichlorisatine ; Chloranilam, and, 



Chlorisatyde, Chloranilammon. 

 Bichlorisatjde ; 



And yet, with all this practical skill in decoction, and 

 accumulative industry in observation and nomenclature, 

 so far are our scientific men from arriving, by any de- 

 coctive process of their own knowledge, at general results 

 useful to ordinary human creatures, that when I wish now 

 to separate, for young scholars, in first massive arrange- 

 ment of vegetable productions, the Substances of Plants 

 from their Essences ; that is to say, the weighable and 

 measurable body of the plant from its practically im- 

 measurable, if not imponderable, spirit, I find in my three 

 volumes of close-printed chemistry, no information what 

 ever respecting the quality of volatility in matter, except 

 this one sentence : 



" The disposition of various substances to yield vapour 

 is very different : and the difference depends doubtless on 

 the relative power of cohesion with which they are en- 

 dowed." * 



Even in this not extremely pregnant, though extremely 



* ' Elements of Chemistry, ' p. 44. By Edward Turner ; edited by 

 Justus Liebig and William Gregory. Taylor and Walton, 1840. 



