400 CARBURETTED HYDROGEN. 



without obtaining inflammable gases, that differ in sp. gr. ; in combus- 

 tibility ; in the quantity of oxygen required to saturate them ; in the in- 

 tenseness of light emitted while they are burning, and in many other 

 particulars. The ablest analysts, however, among whom none stand 

 higher than the gentlemen already named, are of the opinion that only 

 a few species have been distinctly established, and that the apparent 

 diversity arises from innumerable mixtures of these with each other, 

 with other gases, and with various vapors derived from the substances 

 employed. According to this opinion, which is probably correct, 

 the compounds of carbon and hydrogen exist in definite proportions 

 only, " with this peculiarity, that they differ from each other, not so 

 much in the relative proportions of their elements, as in the number 

 of volumes or atoms, condensed into a given volume."* 



3. CONSTITUTION OF THE THREE VARIETIES THAT ARE BEST 

 KNOWN. Dr. Henry. 



Prop, by Prop, in 

 weight, vol. carb. 

 Sp. gr. carb. hyd. hydro. 



1. Carburetted hydrogen, 0.555, 6:2 1:2 } condensed 



2. Olefiant, 0.972, 12:2 2 : 2 > into one 



3. Super-olefiant, 1.458? 18:3 3:3 ) volume. 

 In the olefiant and the super-olefiant the carbon and hydrogen of 



each gas hear the same relation to each other, and the gases differ 

 only in the condensation of their elements. In the olefiant gas, one 

 volume contains two of each of the elements ; in the super-olefiant 

 three. 



The gases that are best known, are divided conveniently into light 

 and heavy carburetted hydrogen gases ; of the former, there is one 

 variety ; of the latter, there are two or more. 



LIGHT CARBURETTED HYDROGEN.f 



1. PREPARATION. 



(a.) By stirring with a stick, the mud at the bottom of any stag- 

 nant water ; bubbles of gas will rise, which may be inflamed by a 

 lighted taper at the surface, or they 'may be collected by an inverted 

 pitcher, filled with water, or by a bottle filled in the same manner, 

 and having a funnel in its mouth. 



This gas contains in mixture, about V f carbonic acid, which 

 may be removed, by washing with lime water, or with solution of 

 caustic potash ; there is also present from yV to ^ - of nitrogen gas. 



* Dr. Henry. 



t Formerly called hydro-carburet and carbonated hydrogen. It is also called 

 proto-carburet of hydrogen, heavy inflammable air of marshes, &c. but the name in 

 the text is generally used. 



