74 ' REroKT — 1884. 



stating experiniontal facts which admit of no tlispnto. These tables 

 bring prominently forward the fact that those names have endured which 

 express no particular opinion on the ultimate constitution of the bodies 

 to which they were applied. Where the names have expressed such 

 opinions the ndvance of knowlrdgo has necessitated change. Sixty 

 years ago the names ' Bi-chloride of phosphorus ' and ' Percbloride of 

 phosphorus' were both applied to the higher chloride of phosphorus. 

 Th.^ I'ormtr name has not lusted because it expressed a particular view 

 as to the nundjcr of atoms in the molecule, which view is no longer 

 accept(!(l. The other name has endured because it merely expressed the 

 experimental fact that the compound contained more chlorine than the 

 lower chloride. To secure permanence for the future this principle 

 should 1)0 acted on. As a general rule those names are to be preferred 

 which have shown the most vitality and have leil to no ambiguity. 

 Wliero fhcre are. firo cniipcamls cinnjtoseil of tlicsanif cJemi'iitu the termiii'itiims 

 ous and ic Hhonhl he ciiidoijed. These terminations have been nsed in the 

 same sense by the great majority of chemists since Lavoisier. The 

 terms 'cuprous chloride,' ' chlorure cuivrenx,' ' Kupferclilnriir ' for the 

 lower chloride of copper, and the terms ' cnpric chloride,' 'chlorure 

 cuivrique,' ' Kupferchlorid ' for the higher chloride hnvo been used by 

 English, French, and ( ierman chemists consistently and without ambiguity. 



The prefixes jiro/o, (7e«/'), &c., introduced into chemical nomenciatui'e 

 by Thomas Thomson, were not intended by him to indicate the number 

 of atoms in a moler "e, but to mark the first, second, or third compound 

 of a series. Thus lie styled the lower and higher chlorides of copper 

 ' pi"OtochIori(le ' and ' dentochloride ' respectively ; but other chemists 

 have styled the higher cldoride the protocldoride, thereby indicating that 

 the molecule contained one atom of copjier, and the lower chloride the 

 dichloride, thereby indicating that the molecule contained two atoms of 

 copper. Where the pretixes yroto, dmdo, &c., are retained they should 

 always be applied in the sense used by Thomson as indicating the first, 

 second, &c., compound of a series. 



A name once given to a particular body should not be taken from 

 that body and applied to another without the gravest reasons for the 

 transfer -reasons accepted by the majority of chemists. The name 

 rarhoiilc tu'iile lias been regularly used to denote the lower oxide of 

 carbon from the time of its discovery. Uiitil quite recently, the name 

 ' carbonic oxide ' served without ambiguity to indicate a particukar 

 ocnipouud. Tills name has lately been applied by certain chemists to the 

 higher oxide of carbon, and a new nsimc has been given to the lower 

 oxide. On account of this transfer the name has become ambiguous. 

 A return to the common nomenclature would involve less change, and 

 would, therefore, bo preferable to the adoption of two new names to avoid 

 this ambiguity. 



Report of the Couimlttee, consisting o/ Professor W. A. Tildkn and 

 Professor H. E. Anyn^mo'SG (Secretari/), appointed for the purpose 

 of investigatiii;/ Isomeric Xapldhalene Derividives. 



The Committee have to report that some steps have been taken towards 

 commencing the work ; but, owing to the unfortunate tire at the London 

 Institution, whereby much of the material was destroyed, and the appoint- 

 ment of Dr. Armstrong to tlie (Jhair of Chemistry at the Central Technical 

 Institute, the results are not yet in a state tit for publication. 



