84 



DENSITIKS or OXYCKN ANH llVDKOIiKN 



i^lobe full of gas, ])ut a voltameter from wliicli the gas was delivered. Secoiully, 

 the fomiiosition of the gas, after weighing and measuring i»ressure, was determined 

 by adequate eudiometric analysis. Lastly, in the computations of the composition 

 of the mixture from the deusity, the deviations of tlie two gases from Roylc's law 

 have l)een taken into account. 



The observations attained a precision which it is hoped will be thought satis- 

 factory. But the constants required in the computation may not be thought suffi- 

 ciently well determined. The uncertainty, however, does not nuich affect the 

 ctmiputed result. The remaining uncertainty will (Imibtless be reuioNcd in time, 

 when the results here obtained will adnu't of re-computation, which will make them 

 more useful. I therefore venture to give the details of the experiments. 



;{. — DKN'SITY OF ELKCTUOI.VIIC (JAS. VOIJ'.Mi;. TE.MI'KKATI i:i;, AND PUKSSHRK. 



The apjiaratus for the measurement of 

 pressure, temperature, and volume was the 

 same as that used in the last preceding detei*- 

 miuations, with some trifling modifications. 



n 



""■"V 



Fk;. 29. — Mcthoii'of^ connecting voUamelcr and rc^ulalitig the 

 current. 



(k''ir<'..j o ^'^f=^S::^o^ 



I'"i<;. 30. — Conntclion t)f j;lobcs to pump, serving 

 to regulate ailinission of gas to the eudiometer. 



For the admission of the gas from the vol- 

 tameter a stopcock had to be inter[)osed, so as 



to keep the pressure in the voltameter equal to that of the atmosphere. In Fig. 

 ■29, h is the fusible metal valve by which hydrogen is to be admitted to the 

 globes; to this. is fu.sed the stopcock ;/, which, during the operation of tilling, 

 was immersed in sidphuric acid. 



The connection of the globes to the pump was moditicd so as to serve two 

 purposes. In oi-der to admit to an exhausted eudiometer an ap[>iopiiate (|uantity 

 of the gas, some stopcock was necessary ; but one which could possibly leak w as 

 objectionable. The api)aratus was therefore constructed a.s shown in Fig. 30. At 

 (I is the tube leading to the three globes in the ice. F)ut the connection of this 



