216 



suitable capillary tube with rubber (•oiiuection:-;. A niertury liuri't. arranged 

 to receive the gas, was connected to the other end of the quartz tulie in a 

 similar manner. Pinch cocks, one on the buret and one on the pipet, con- 

 trolled the connections with the quartz tiibe. The buret was provided with 

 a water jacket which was connected at its lower end with a level bdttle so 

 arranged that the water could be drawn out and then passi'd back Into tli<' 

 water jacket. This circulation and tliorough mixing of the water were 

 necessary to prevent unequal temperatures between tlie top and bottom of 

 the buret. The water jacket was improvised from the outside of a Liebig 

 condenser. A thermometer, wliich showed the temperature of the water 

 and gas, was suspended about midway of the buret inside of the water 

 jacket. The quartz tube was heated by a bunsen burner provided with a 

 wing tip which produced a broad flame. An asbestos board was suspended 

 about 5 mm. above the quartz tube, to lessen tlie radiation of heat. The 

 manipulation was : The temperature of the gas in the pipet, that is the 

 temperature at which it was measured, was carefully read. Tlie pinch- 

 cock connecting the buret to the quartz tube was opened and the burner 

 was lighted for three minutes. The increase in volume of the air iu the 

 quartz tube produced by the heat, was cared for in the buret. The pinch- 

 cock connecting the pipet to the quartz tube was opened and the level bottle 

 was raised so that the gas and o.xygen passed slowly and regularly over the 

 glowing platinum, generally abotit three minutes being required. In no 

 case was there any indication of an explosion in the pi])et even when the 

 velocity of the gas was greatly increased. The level tube on the buret was 

 raised and the level bottle on the pipet was lowered so that the gas was 

 forced back from the buret into the pipet. The gas was then again passed 

 through the quartz tube over the glowing platinum into the buret. The 

 flame and the asbestos board were removed and water was poured upon the 

 quartz tube to cool it. After the quartz tube had reached room tempera- 

 lure, the pincbcock (•onn('( ting (lie buret and quartz tulu^ was closed. The 

 mercury in the bui-et and level tube was leveled. The water in the water 

 jacket was passed back .nnd forth by means of the level buttle until the 

 thernioineter iu the water jacket showed constant teuijierature. The mer- 

 cury in tlii^ liuref and level lube was again cai'i'fully leveled and the volume 

 of gas was I'ead. The liual gas volume was always corrected for variation 

 from the initial teniiierature. 



'{'he i)rocess as described nlioxc w.is ti'ied with pur(^ hydrogen gas. 

 which was pi-eparcd li.\ the action n\' bdiji'd dilute sulphuric ncid U]ioii 



