Mr. W. Odling on Chemical Notation, 383 



9 : 18*25 : 1 — a conclusion for which I certainly did not expect 

 to be reproached by a thermo-molecular physicist. 



Now the determination of this point depends almost entirely 

 upon a consideration of the molecular relations subsisting between 

 water, hydrate of sodium, and oxide of sodium, and between 

 water, alcohol, and ether (for I have yet to learn when " the 

 chemical evidence with respect to the formation of ether and 

 decomposition of alcohol " ceased to be " deemed of import- 

 ance"); that is to say, upon the question whether the molecules 

 of hydrate of sodium and hydrate of ethyle contain double the 

 amount of oxygen, or the same amount of oxygen as the mole- 

 cule of water * in which last case the three molecules will 

 be represented by integral formulae thus, H 2 0, HNaO, and 



H(C*H 5 )0; or by fractional formulas thus, HO*, H*Na*0*> 



and H*(CH**)0**. 



But this is a question which it is obviously impossible to argue 

 with a gentleman who, in opposition to the interpretation which 

 has gradually forced itself upon the reluctant minds of a majority 

 of the most distinguished chemists of all nations, disposes of the 

 whole matter offhand by asserting ex cathedra, " Now the fact is, 

 that two molecules of water are engaged in forming one molecule 

 of the hydrate " f- 



It would at the same time be gratifying to learn how and when 

 this very decisive fact was ascertained, and by whom. Probably 

 by some favoured " mathematical student of thermo-molecular 

 physics," from whose transcendental faculties nothing chemical 

 is concealed, rather than by a mere plodding chemist whose most 

 inspired notions are but of the earth, earthy. 



In conclusion, I would suggest to Mr. Waterston that when 

 he again condescends to direct, with no uncertain voice, poor 

 benighted chemists into the right path, he should first make 



* The volume of a chemical equivalent of sodium (j£- = y-J has not 

 been ascertained, but from analogy is believed to be the same as that of 

 hydrogen and ethyle ; whence we have Gerhardt's molecular formulae for 

 the sodic derivatives of hydrogen, muriatic acid, water, ammonia, marsh- 

 gas, alcohol, and nitric acid, namely Na 2 , NaCl, NaHO, NaH 2 N, NaH 3 C, 



NaH 5 C 2 0, and NaNO 3 respectively \ or in fractional formulae, Na, Na'Cl*' 



Na^H^O*, Na^HN^ Na^H^C*, Na^H^CO*' and Na*N*0 14 respect- 

 ively. Vide columns I. and II. 



t In criticising a sentence from the Supplement to Mr. Graham's 

 ' Elements of Chemistry,' Mr. Waterston writes, " In the above extract 

 HKB represents one molecule of the hydrate of potash, but HHG repre- 

 sents two molecules of water, and KK9 two molecules of anhydrous potash." 

 Be this as it may, I am permitted by Mr. Watts, the author of the Sup- 

 plement, to state that the three formulae were meant to express a single 

 molecule each, the three quantities represented being exactly comparable. 



