OXYGEN. 



247 



FIG. 32. 



3. A well cleansed Florence oil flask, the edges of the 

 mouth of which have been heated and turned over so as to 

 form a lip, with a bent glass tube and perforated cork fitted 

 to it, as in the figure, forms a convenient retort in which 

 about half an ounce of chlorate of potash may be heated by 

 means of the Argand spirit lamp. The salt melts, although it 



contains no water, and 

 when nearly red hot, 

 emits abundance of 

 oxygen gas. At one 

 point of the decompo- 

 sition, the effervescence 

 may become so violent 

 as to burst the flask, 

 especially if the exit 

 tube be narrow, unless 

 the heat be moderated. 

 The chlorate of potash 

 parts with all the oxygen it possesses, which amounts to 37 

 per cent, of its weight, and leaves a white hard salt, the chloride 

 of potassium. From an atomic statement of the composition 

 of this salt, one equivalent of it (1532 parts) will be observed 

 to contain six equivalents of oxygen (600 parts), five in the 

 chloric acid and one in the potash, the whole of which come off, 

 leaving an equivalent of chloride of potassium (932 parts) : 



Half an ounce of chlorate of potash should yield 270 cubic 

 inches or nearly a gallon of pure oxygen gas. 



Properties. Oxygen gas is colourless, and destitute of odour 

 and taste. It is heavier than air in the ratio of 1 102.6 to 1000 

 according to the weighings of Dulong and Berzelius; 100 cubic 

 inches of air being taken to weigh 3 1 grains at the temperature 

 of 60 and with the barometer at 30 inches, 100 cubic inches 

 of oxygen gas will therefore weigh 34.18 grains. One cubic 

 inch weighs 0.3418 or very nearly l-3rd of a grain. It has 

 never been liquefied by cold or pressure. Oxygen is so 

 sparingly soluble in water, that when agitated in contact with 

 that fluid no perceptible diminution of its volume takes place. 

 But when water is previously deprived of air by boiling, 100 



