48 Berzelius and Didong on Recent Determinations [July,, 



estimating the time from four o'clock on the shortest day and 

 nine o'clock on the longest. 



I here take my leave of the subject as a controversialist. My 

 statement of the advantages of oil gas, and the observations 

 that have been made upon it, are before the public, and if I have 

 succeeded in drawing attention to the subject, my end is an- 

 swered. I am only desirous of seeing the two fairly in competi- 

 tion, and then, time and experience will enable the public to 

 form their judgment of which is preferable, and that which they 

 find so will be most generally adopted. It has been from the 

 strongest persuasion of the superiority of oil gas over coal gas, 

 that I have been induced to come forward in its recommenda- 

 tion. Whenever I am convinced that I am in error, I will most 

 readily acknowledge it; though, I must observe, that it must be 

 by very different arguments from those which have been brought 

 forward that such conviction can reach my mind. 



I am, Sir, your's truly, 



M. Ricakoo. 



Article VIII. 



Extract from a Paper, entitled, f Recent Determination of the 

 Proportions of Water, and of the Density of some Elastic 

 Fluids:' By MM. Berzelius and Dulong * 



The authors of this memoir remark, that the degree of exac- 

 titude to which chemists of the present day aspire has led them 

 to adopt the relation between the weights of the elements of 

 water as a standard of comparison. They then allude to the 

 experiments of MM. Biot and Arago ; and conclude, that if 

 T327, the proportional number assigned by them to hydrogen, 

 be inaccurate, it must have been derived either from an erro- 

 neous estimate of the specific gravity of hydrogen or of oxygen, 

 or of both; observing, that the relation in volumes has this re- 

 markable advantage, that being supported by a general law, it 

 does not admit of any error. 



The first thing to be resolved upon was, the method of obtain- 

 in°" hydrogen gas in purity. The authors observe that for this 

 purpose it is not requisite to use distilled zinc, it not being prefer- 

 able to the zinc of commerce. They procured the gas which 

 they employed by acting upon zinc with sulphuric acid and 

 water ; and they observe that if it be passed through a tube con- 

 taining caustic potash slightly moistened, it loses its smell 

 completely, and is rendered perfectly pure ; it may then be dried 

 by passing it over muriate of lime. Hydrogen gas thus obtained 



• From Annates de Chime et de Physique. 



