ACCOUNT OF A SEW KUDIOMETKR. 



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wli>n thefe falls cannot be obtained in a ftate of abfolatc pu* 

 pity the common or mixed fulphate of iron may be employed.' 

 One cubic inch of moderate!) itrong impregnated folution is £fle&. 

 capable of absorbing five or iix cubic inches of oxigen, in- 

 common procefles ; but (he fame quantity mull never be em- 

 ployed for more than one experiment. 



A number of comparative experiments made on the confti- Comparative cx- 

 tution of the atmofphere at the Hotwells, Briflol, in Jul}', Au- [J^** ' ° r 

 gull, and September, 1800, with phofphorus, fulphurets of 

 alkalis, and impregnated folution, demonflrated the accuracy 

 of the procefles in which the laft fubflance was properly em- 

 ployed. The diminutions given by the fulphurets were indeed 

 always greater by a minute quantity than thofe produced by 

 phofphorus and impregnated folutions : but the reafon of this, 

 will be obvious to thofe who have iludied the (abject of eudio- 

 metry. In no inftance was it found 100 parts in volume of air 

 contained more than 21 of oxigen : and the variations con- 

 nected with different winds, and different ftates of tempera- 

 ture, moifture, &c. were too fmall, and too often related to 

 accidental circumftances, to be accurately noticed. 



In analyfing the atmofphere in different places, by means of No remarkable 

 impregnated folutions, I have never been able to afcertain any SJJjJJfo ^ 

 notable difference in the proportions of its constituent parts, air of various 

 Air, colledcd on the fea at the mouth of the Severn, on Oc- g£*? t0 its 

 tober the 3d, 1800, which muft have palled over much of the 

 Atlantic, as the wind was blowing ftrong from the weft, was 

 found to contain 21 per cent, of oxigen in volume; and this 

 was nearly the proportion in air fent from the coaft of Guinea, 

 to Dr. Beddoes, by two furgeons of Liverpool. 



If we compare thefe refults, with the refults gained more — and confe- 

 than twenty years ago, by Mr. Cavendifh, from experiments S^y '£i t y ** 

 on the compoiition of atmoipherical air, made at London and depends on iub- 

 Kenfington; confidering, at the fame time, the refearches of ^^^Ya 

 Berthollet in Egypt and at Paris, and thofe of Marti in* Spain, it, 

 we fliall find ftrong reafons for concluding, that the atmofphere, 

 in all places expofed to the influence of the winds, contains 

 very nearly the fame proportions of oxigen and nitrogen : a 

 circumflance of great importance ; for, by teaching us that 

 the different degrees of falubrity of air do not depend upon 

 differences in the quantities of its principal conftituent parts, 

 it ought to Induce us tp inftitute refearches concerning the dif- 



S ferent 



