On some Comhinntions of Plalinum. 333 



fluid reddened litmus, and had an acid taste. The gas rendered 

 lime-water turbid, and was in part absorbed by vvater and by 

 ammonia; and the unabsorbed portion exhibited properties si- 

 milar to those of nitrogen. These results seemed to prove, that 

 the powder contained acid and inflammable matter; but they 

 were not sufficiently uniform to enable me to place much reli- 

 ance on them. I then used very small glass retorts, varying in 

 capacity from -%- to -^^ of a cubic inch, and decompc.ed the 

 powder over pure vvater and over mercury; but the results were 

 most satisfactory when I operated over mercury. From two ex-^ 

 periments of this kind, which I beg briefly to detail, as they very 

 nearly agree, I think I may venture to state the composition of 

 the powder under examination. 



Experiment 1. Ten grains of the powder were decomposed 

 in a little retort, over dry mercury, by the heat of a spirit lamp. 

 On the first impression of the heat, gas was disengaged, and 

 shortly after, the interior of the retort assumed a reddish yellow 

 colour (like that exhibited by the vapour of fuming nitrous 

 acid), and small drops of a colourless fluid condensed in the neck 

 of the retort. After tlie utmost heat of the lamp had been given 

 to the retort, it was suffered to cool, and the results were im-^ 

 mediately examined. 



(a) Examination of the Gas. 



The gas remaining in, the retort made an ignited piece of wood 

 glow brighter; that which came over (deducting the common 

 air) was -/^^-^ of a cubic inch, which diminished to -j-^g on being 

 transferred to water and agitated. -f~ of the unabsorbed gas, 

 on being mixed with an equal volume of pure hydrogen, and fired 

 by an electric spark, diminished to -fTj^. Hence, the unabsorbed 

 portion of gas contained more oxygen than could have been fur- 

 nished from the common air of the retort. 



From other experiments, the gas absorbed by water was found 

 to be carbonic acid ; it rendered lime-water turbid, was absorbed 

 by ammonia, and again disengaged by muriatic acid. 



(b) Examination of the Fluid. 



The fluid which rose in the neck of the retort reddened litmus 

 paper, and resembled the nitrous acid in odour, colour, and taste. 

 It acted upon the mercury in contact with the retort, and when 

 Vv'ashed out by pure water, the solution did not affect the nitrate 

 of barytcs, or silver. 



(c) The platinum was perfectly reduced, and its particles 

 formed a loosely coherent mass, which could not be removed until 

 the bulb of the retort was broken. It weighed 9[f grains, and 

 ssuflfered no diminution on being again heated to redness in a 

 platinum cup. 



Exfjcri- 



