204 Mr. A. M. Herbert on the Effect of Hydrogen on 



the gas, or mixed gases, was forced through the discharge- 

 tube, after bubbling through strong sulphuric acid to get 

 rid of most of the moisture present. A slow current of gas 

 was maintained so as to prevent the accumulation in the 

 discharge-tube of any products of chemical decomposition 

 due to the passage of the spark. 



The spark passed between platinum-iridium electrodes 

 which were about 3 mm. apart ; these were fused into the 

 bulb of the discharge- tube, the diameter of the bulb being 

 about 4 cm. One of Apps's induction-coils was used which 

 gave a spark of about 3 inches between its terminals in air, 

 when four Tudor cells (2 volts each) supplied the primary 

 current. 



A small leyden-jar, the outer tinfoil area being about 

 280 sq. cm., was included in the circuit. In all the experi- 

 ments the spark was taken at atmospheric pressure. 



The following results were obtained, each set of experi- 

 ments being repeated several times with similar results ; the 

 effects upon the two red lines are noted : — 



A. Spark in mixture of Carbonic Acid Gas and Hydrogen. 



(i.) 2£ pares H in 25 parts mixture=10 per cent. H. [Hydrogen line stronger than 



carbon line.] 



,, =20 per cent. H. [Hydrogen line strong, carbon 



line faint.] 



,, =30 per cent. H. [Hydrogen line very strong, 



(approx.) carbon line very faint.] 



;j =50 per cent. H. [Carbon line hardly distin- 



guishable.] 



„ =5 per cent. H. [Lines about equally strong ; 



hydrogen, if anything, 

 slightly stronger.] 



A second set of experiments gave the following results : — 



(i.) 2£ parts H in 25 parts mixture =10 per cent. H. [Hydrogen line slightly the 



stronger.] 



(ii.) 6 ,, 20 ,, =30 per cent. H. [Hydrogen line very strong, 



carbon line very faint.] 



(iii.) 10 „ 25 ', =40 per cent. H. [Carbon line hardly distin- 



guishable.] 



(iv.) 12^ ,, 25 „ =50 per cent. H. [Carbon line hardly visible.] 



(v.) ^ ,, 50 „ =1 per cent. H. [Carbon line very strong; 



hydrogen line very faint, 

 but quite distinct.] 



(vi.) 1 ,, 20 ,, = 5 per cent. H. [Lines about equally strong ; 



carbon, if any thing, slightly 

 stronger.] 



The percentages given do not, of course, pretend to any 

 great accuracy ; thus there did not seem to be much dif- 

 ference in the effects between 40 per cent, and t 50 per cent, 

 of hydrogen. 



(ii.) 5 



25 



(iii.) 5 



17 



(iv.) 7 



14 



(v.) 1 



20 



