OF THE VIBRATIONS OF AN INVARIABLE PENDULUM. 



229 



Wlience it appears that at the same height of the barometer, 30.193 inches, 

 the pendulum made 8.515 vibrations per diem more in hydrogen gas than in 

 atmospheric air ; the temperature of the gas being 39°.32, and of the air 38°. 1. 



The hydrogen gas was obtained under Mr. Newman's superintendence, by ., 

 the action of zinc upon dilute sulphuric acid ; and was collected in a gasometer* t 

 previous to its transfer into the apparatus, which was effected through the 

 metallic pipe usually connected with the air-pump. The cylinder containing 

 muriate of lime was made a part of the communication between the apparatus 



and the gasometer. 



Exp. VIII.— February 10th, 11th, and 12th. Clock gaining 4-" 14^38. - 



The hydrogen having been again pumped out till the gauge showed 0.7 

 inch, a fresh atmosphere of hydrogen was introduced by Mr. Newman with 

 every possible care to ensure its purity; when the following observations 

 were made. ' ; ' ; 



Thermometers. 



Included 

 Barom. 



Times of 



Disapp. Re-app. 



Coincidence. 



Arc registered and 

 true Arc. 



Mean 

 Interval. 



Correc- 

 tion for 

 Arc. 



Reduct. 



to 36°. 



Corrected 

 Vibrations 



at36- 



Mr. 

 Tayior.'S 



1 



2 

 3 



80 

 81 

 82 

 83 

 84 

 85 

 86 



39.8 



39.7 



29.84 



39.7 



39.7 



29.82 



15 58 

 24 23 

 32 48 

 23 25 

 32 04 

 40 42 

 49 07 

 57 44 

 06 20 

 14 51 



16 15 



24 39 

 33 05 



25 17 

 33 54 

 42 21 

 50 40 

 59 04 

 07 34 

 15 63 



11 24 31.33 



V22 49 55.43 



Div. o 



0.765 = 0.92 



0.107 = 0.128 



■507.705 



+0.35 



+ 1.58 



86314.95 



39.75 



29.83; Index + 0.32; Reduction to 32° — 0.03; = 30.12. 



86314.95 



A bottle was then carefully filled with the hydrogen gas from the apparatus 

 by Mr. Newman, and conveyed by him to Mr. Faraday at the Royal 

 Institution for examination, from whom I have since received the following 

 note. " I have examined the hydrogen gas, and find no appreciable quantity 

 of air in it. If it contains any, it is less than j^cdth part ; and this I think will 

 be as nothing in your experiments." 



Tlie remainder of the hydrogen was then pumped out of the apparatus to 



