ACCOUNT OF A NEW EUDIOMETER. 87 



affords, toward the diseoveiy of others, and consequently Hence eudio- 

 the composition, or analysis of bodies before held to be sim- mU chatteii« 

 pie, it will not appear a matter of surprise, that the subject tion. 

 of eudioinetry should have obtained a considerable degree 

 of attention from modern philosophers. 



This would be an improper place to enumerate all that Whathasbeea 

 has been done, or proposed, by different men of eminence, ' !on . e on the 

 towards the production of something like a perfect system 

 on this important subject; yet some allusion to their labours 

 appears to be indispensible, and will be the means of pre- 

 venting some circumlocution in our farther progress. 



Hales* appears to be the tirst who observed absorption Hales. 

 to take place in common air, on mixing it with air obtained 

 from a mixture of Walton pyrites and spirit of nitre; and 

 that in this process from being clear they became " a red- 

 dish turbid fume." 



Dr. Priestley, as he informs us in his Observations on dif- Priestley. 

 Jerent kinds of 'Airt, was much struck With this experiment, 

 but never expected to have the satisfaction of seeing this re- 

 markable appearance, supposing it to be peculiar to the 

 Walton pyrites, till encouraged by a suggestion of Mr. Ca- 

 vendish, that probably the red appearance or the mixture 

 depended upon the spirit of nitre only, he tried solutions of 

 the different metals in that acid, and, catching the air which 

 was generated, obtained what he wished. To the air thus 

 produced he gave the name of nitrous air; and, from its 

 possessing the properties of absorbing that portion of atmos- 

 pheric air which he calls dephlogisticuted, first proposed its 

 being used as a test for ascertaining tiie purity of air. Kis The first eudi#- 

 znethod of proceeding was ingenious and simple; known meter « 

 quantities of the air to be tried, and of nitrous gas, being 

 mixed, were admitted, after the diminution of volume occa- 

 sioned by their union, into a graduated tube, which he de- 

 nominated a eudiometer. 



It was with the test of nitrous gas, that Mr. Cavendish J Cavendish's 

 made his masterly analysis of the air at Kensington and common°air. 

 'London ; and by many laborious processes and comparative 



* Statical Essays, Vol. I, p. 224 5 Vol II, p. 280. 

 J Phil. Trans, for 1783, f Phil. Trans, for 1772, p. 210. 



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