Henry's Chemistry. 337 



" 3dly. There are many examples in which bodies unite in one 

 proportion only; and in all such cases, the proportion of the ele- 



or from Carrara, or from the Pentelic hill, or from Sutherlandshire, or from 

 any other part of the world, is composed of 28 parts of lime united to 22 of 

 carbonic acid : and acain 22 parts of carbonic acid, whether extracted from the 

 said marble, or generated by the respiration of animals, or by the combustion 

 of coal or wood, or of the diamond, whether poured forth from the surface of 

 fermenting liquors, or issuing from fissures in the earth, consist in all cases of 

 6 parts of carbon combined with 1G of oxygen. But it often occurs that bo- 

 dies combine in more than one proportion, and this happens to be the case 

 with carbon and oxygen, which besides carbonic acid produce carbonic oxide. 

 Now in respect to the latter, if we still suppose the weight of carbon to be 6, 

 that of oxygen is 8, that is just half the quantity existing in carbonic acid ; and 

 as ou the one hand we find the proportions of the elements of the same com- 

 pound always in the same relation to each other ; so wheu one substance com- 

 bines with another in different proportions, to form different compounds, the 

 numbers representing the greater proportions, are exact simple multiples of 

 that denoting the smallest proportion. This doctrine of multiples is of so much 

 consequence that we shall press another instance or two upon the attention of 

 our uninitiated readers. There are two oxides of mercury, the black and the 

 red ; in the former 200 parts of the metal are united to 8, and in the latter to 

 16 of oxygen. There are 5 compounds of nitrogen and oxygen, and if we 

 assume the weight of the nitrogen to be 14, that of the oxygen in the several 

 compounds is respectively S, 16, 24, 32, and 40 ; that is, one, two, three, four, 

 and five times 8. So much for the doctrine of multiples. To explain another 

 term used in these disquisitions, let u» go back to the marble and Epsom salt. 

 In the former we have discovered 22 parts of carbonic acid united to 28 of lime, 

 forming 50 of carbonate of lime or marble, and in the latter we find 40 of sul- 

 phuric acid combined wjlh 20 of magnesia, producing 60 parts of sulphate of 

 magnesia or Epsom salt. If we now suppose these elements differently ar- 

 ranged, forming, for instance, carbonate of magnesia and sulphate of lime, we 

 shall find them obedient to the same proportions, that is, 22 of carbonic 'aciil 

 will unite to 20 of magnesia to form 44 of carbonate of magnesia; and 4o of sul- 

 phuric acid will he required by 28 of lime to form 68 of sulphate of lime. 

 Hence is is that the numbers which we have employed to represent the com- 

 bining weights of the above substances have been termed equivalent numbers. 

 If we now draw out a list of commonly occurring elementary or compound bo- 

 dies, and affix numbers to them representing the smallest proportions in which 

 they combine, in reference to some substance assumed as unity, it is obvious 

 that such a list will present much useful information ; for instance, 



Hydrogen . • 1 Lime . . . 28 



Oxygen ... 8 Soda .... 32 



Water ... 9 Phosphoric acid 28 



Sulphur . . . U> Nitric acid . . 54 



Sulphuric acid . 40 Potassa ... 48 



Magnesia . . 20 



Now from this table it will be manifest that 9 parts of water consist of 1 hy- 

 drogen and 8 oxygen. That ](» parts of sulphur combined with 24(that is, 3 times 

 H; of oxygen constitute 40 of sulphuric acid ; and that 40 of sulphuric acid will 

 neutralize 20 of magnesia, 28 of lime, 32 of soda, and 48 of potassa, whereas the 

 nmo weight of these alkaline substances will be neutralized by 54 of nitric 

 acid, and by 28 of phosphoric acid. But whilst proceeding with these lucubra- 

 tions we bad almost forgotten the excellent illustrations of the uses and appli- 

 tioiiB qf such a system of numbers which Dr. Wollaston has annexed to his 

 description of his logometric scale of chemical equivalents, published in the 

 Philosophical TransactioTU for 1814, to which \vc refer our readers as infinitely 

 luminous, and as rendering any extension of our remarks unnecessary. 

 Vol.. XVI. Z 



