42 nKi'ouT— 1884. 



rendinc'srt witli which it ciin bo removed from a componnd in flu; form of 

 wiitcr. Laurent thus conchides that oxides, liydrogeu suItH, and other 

 salts may with perfect propriety be classed together. 



Acii» AND Basuj Sat/is. 



Roiiolle was tho first to call attention to the fact that a given acid 

 und hnso can eoinhine in ditfercnt proportions. Ho p'-epared tho salt 

 now known as KllSO., from potassic siilpliato (tartre vitriol*'"), and in- 

 vestigated its properties, i le distinguislied three different classes of salts. 



1. He calls 'neutral salts with an excess or superabandanoo of acid,' 

 Halts which, besides the amount of acid which makes them quite neutral, 

 have an additional quantity of av'u\ Cdiiiliiiifd with them, and ho knows 

 that this o-xce.ss of acid has its point of saturation. Such salts, ho says, 

 are as a rule more soluble than the corresponding salts of his third class. 



2. What wo call neutral salts ho calls ' sels neuties parfaits,' or ' sols sales.' 

 ii. Tho third salts he calls ' neutral salts with tho smallest possible 

 quantity of acid,' At first sight these classes seem to correspond with 

 what wo now call acid, neutral, and basic salts, but Kouello's examples 

 show that this is not tho case. Tho only acid salts which ho seems to 

 have known is tho hydric potassic sulphate which he was the first to 

 prepare, and he puts in tlio same class with it mercuric chloride and other 

 persalts, while calomel is given as tho typical instance of a salt with tho 

 Kmallest possible amount of acid. This confounding of hydrogen double 

 salts with salts containing as largo an amount of acid as tho base can 

 saturate continued up to tho end of the century. 



1787. — In course of time, however, more salts of tho two abnormal 

 classes were discovered. In tho 'Morveau-Lavoisier* nomenclature, salts 

 of tho acid class wore called acidulous salts, thus: KHS04=sulphate 

 potassiqne acidule, while salts with an excess of tho basic constituents 

 wore called alkaline, or supersaturated salts. Salts generally are called 

 neutral salts. These terms were translated directly into l^higlish in 

 Pearson's translation of 1704. 



In an essay on 'Chemical Nomenclature,' published in 170G by 

 Stephen Dickson, be proposes to denote the predominance of acid and 

 base respectively by prefixing tho prepositions ' super-' or ' sub-' to tho 

 adjective the name of tho acid. 



Thus:— 



KHSO,=snpervitrIolated vegetable alkali. 

 Cu2CU=submuriated copper. 



1809. — In Murray's ' System of Chemistry ' we find that a distinction 

 is at last made between the relation of KjSOj to KHSO.1, and that of 

 HgClo to HgaClj. Ho says that submuriato is not a good name for this 

 last salt, as it contains enough acid to make it neutral. He does not, 

 however, propose a systematic name for this substance, but calls it mild 

 muriate of mercury. Similarly, ho rejects tho name of super-snlphate of 

 iron, and distinguishes the two sulphates as red and green sulphates. 



1810. — In the fourth edition of Thomson's treatise, we find yet 

 another method of naming these salts. Thomson, following Lavoisioii's 

 theory of oxygen acids, considers that the difference between calomel and 

 corrosive sublimate is that in tho latter the mercury is in a more highly 

 oxidised condition. He therefore calls HgCl., oxymuriate of mercury. 

 This leads to a confusion with chlorate of mercury, then called by some 



