Advanced inorganic chemistry / by G.H. Bailey ; edited by William Briggs.

  • Bailey, G. H.
Date:
[1898]
Catalogue details

Licence: Public Domain Mark

Credit: Advanced inorganic chemistry / by G.H. Bailey ; edited by William Briggs. Source: Wellcome Collection.

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    upper part of the beaker and gradually fill it to the mouth, pressing out the air before it. The arm of the balance will at the same time be deflected, and the beaker in question will rise. Small weights should now be added till the arm becomes horizontal again. If the beakers are of the size prescribed above, about 6 grammes will be necessary for this. If we continue to pass the gas after this, the equilibrium of the balance will not be disturbed, but on withdi-awing the tube the arm bearing the in- verted beaker will soon begin to fall again, showing that it is now gaining weight. This is due to the diffusion of the hydrogen out of the beaker and its replacement by air, and it will be seen how gradual such a process is. We have seen then by this rough experiment that when 5 litres of air are replaced by 5 litres of hydrogen, a loss of weight occurs equal to about 6 grammes, which represents that a litre of hydrogren is approximately 12 grammes Zig'^ie? than a litre of air. When the whole of the hydi-ogen has been cleared out of the inverted beaker and replaced by air, pass carbon dioxide down- wards into the other beaker, and note that it is depressed, show- ing that whilst hydrogen is much lighter than air, carbon dioxide is heavier than air. The weight requued to restore equilibrium in this case will be found to be approximately 3 grammes. To determine the weight of gases more accurately; suspend from the arras of a deUcate chemical balance two globes fitted with stop-cocks, and having a content of about 500 c.c. In order to eliminate corrections for buoyancy of the air the two globes should be as nearly as possible similar. Exhaust one of the globes carefully at the air-pump, and then close the stop-cock. Now attach it at one arm of the balance, and the other globe filled with dry air at the other arm, and note the weight to be added in order to bring it into equipoise. This will be the weight of 500 c.c. of air, say 0-618 gramme at the temperature and pressure prevailing at the time, say 9° C. and 750 ra.m. pressure. Now attach the vacuous globe to a supply of dry hydrogen and again equipoise. Instead of 0-618 gramme we find only 0-575, and we have the data necessary to determine— (1) The relative density of hydrogen and air.