ISO On the Specific Gravity of the Gases, [March^ 



2. The specific gravity of phosgene gas, as stated in the table, 

 is obtained by adding together the specific gravities of chlorine 

 and carbonic oxide gases ; for according to Mr. John Davy it is 

 composed of equal measures of these two gases condensed into 

 half their bulk. 



3. The specific gravity of silicated fluoric acid is the result of 

 Mr. John Davy's experiments, given in the Philosophical Trans- 

 actions for 1812, part 2d. An account of these experiments is 

 given in the present number of our Journal. 



4. The specific gravity of chlorine is the result of my own 

 experiments, made with as much care as possible. Other che- 

 mists have given it lower. I presume their gas contained a 

 mixture of euchlorine gas. My gas was procured from a mixture 

 of oxide of manganese, com.mon salt, and sulphuric acid, and 

 was passed through water ; so that neither muriatic acid gas nor 

 euchlorine gas could be mixed with it. 



5. Nitrous acid gas is given from the experiments of Sir 

 Humphry Davy in his Researches, He obtained this gas by 

 saturating nitrous gas with oxygen in a glass globe, and knowing 

 the specific gravity of the two gases employed, and the conden- 

 sation, it was easy to determine the specific gravity of the gas 

 formed. The number in the table would admit of some slight 

 corrections ; but as this gas is never united with determinate 

 bulks of others, its specific gravity is of comparatively little 

 consequence. 



6. Euchlorine gas Vv-as weighed by Sir Humphry Davy when 

 originally discovered. It was this determination, given in the 

 Philosophical Transactions for 1811, that I have employed. 



7. The specific gravity of fiuoboracic acid was determined by 

 Mr. John Davy, and the result which he obtained published in 

 the Transactions for 1812, part 2d. We have given an account 

 of his experiments in this third number of our Journal. 



8. The specific gravities of the vapour of ether and of alcohol 

 were communicated to me by Mr. Dalton by letter. I do not 

 know the method which he employed to determine them. 



9. I have taken the specific gravity of sulphurous acid gas as 

 determined by Sir Humphry Davy (Phil. Trans. 1812, part 2d) 

 as the latest and most accurate, Kirwan stated it as high as 

 2*2553 ; but from his own account of his experiment little 

 reliance could be placed in it. 



10. The specific gravity of nitrous oxide is given as it v.^as 

 determined by Sir HumpliryDavy in his Researches. BerlhoUet 

 states it as low as 1-3029 ; but it is probable that the gas which 

 he examined contained a mixture of common air. 



11. 1 have given the specific gravity of carbonic acid gas 

 according to the experiments of -Saussure (Ann. de Chim. vol. 



