230 E. W. Morley — Volumetric Composition of Water. 



opened. A good exhaustion was now produced back to the glass 

 stop-cocks. The valve shutting off n, fig. 2, was now opened, 

 as well as the stop- cock of the globe e, (but of this elsewhere), 

 and hydrogen admitted to a tension of ten or twenty centi- 

 meters. Then the valve o, fig. 1, was closed, and a good ex- 

 haustion again produced in the whole apparatus, m, n, and e, 

 fig. 2. The degree of exhaustion thought proper depended on 

 circumstances. The pump was then shut off', the fusible metal 

 valve opened, and hydrogen admitted till its pressure was a 

 little greater than that of the atmosphere. The valve j being 

 then closed, the hydrogen in n was ready for use. 



The apparatus for preparing oxygen is not shown. Potas- 

 sium chlorate was placed in a hard glass tube ; this was fused 

 to a similar tube containing finely divided silver and heated in 

 a furnace. These two tubes were connected to the soft glass 

 tubes of the remaining apparatus by a ground joint. First was 

 a tube like g and A, fig. 1, with a fifty per cent solution of 

 potassium hydrate, and then a similar tube with glass beads and 

 sulphuric acid. Then followed a stop-cock used to keep the 

 pressure in the apparatus so far nearly equal to that of the atmos- 

 phere. This stop-cock was lubricated with syrupy phosphoric 

 acid, and was followed by a tube filled with phosphorus pen- 

 toxide, and ending at the tube b, tig. 2. This tube could be 

 connected to the globe e, fig. 2, by making a fused joint at the 

 proper place. It was also connected to the three mercurial 

 valves and also to a system for storage of oxygen identical 

 with that for hydrogen. The manipulation in filling this sys- 

 tem with oxygen was much like that for filling with hydrogen. 



Apparatus for extracting hydrogen and oxygen- from the 

 stores, and for preparing to determine residual nitrogen in 

 hydrogen. — At <?, fig. 2, is a mercurial valve which can be 

 opened under difference of pressure. Those at the left of this 

 figure can be opened only when the two pressures are equal. 

 It also permits some regulation of the rate of flow. The 

 descending tube which is connected directly to n contains 

 a part so narrow that only a certain amount of gas can pass in 

 a minute ; the amount is calculated according to the size of the 

 wider tube next following. Suppose this tube and those fol- 

 lowing to the right to be vacuous ; when the mercury in the 

 valve o is lowered so as to uncover the end of the descending 

 tube where it enters the wider tube, gas will bubble up through 

 the mercury which stands in the wide tube, and the rate can 

 be adjusted by altering the level of the mercury. When the 

 flow is rather rapid, the bubbles burst with such force as to 

 throw some mercury over into the short wide tube at the right, 

 whence it flows back by the tube provided for the purpose. 

 By the use of this valve, it is possible to exhaust everything 

 to the right of o, and then to introduce any required volume of 



