History of Air-Analysis 9 



The application of the nitrous-oxide method for determining the degree 

 of phlogistication of the air as first brought out by Priestley immediately 

 led to an extensive interest in this problem on the part of a number of in- 

 vestigators. As Priestley's observations were but roughly quantitative, 

 the Abbe* Felice Fontana 1 in Italy constructed an instrument permitting 

 a much greater accuracy in the measurement of the contraction in volume 

 and determined the quantity of oxygen contained in air by absorption 

 with nitric oxide, obtaining results showing from 18 to 25 per cent. Using 

 this instrument, a number of investigators began studying the absorption 

 due to nitric oxide, an absorption that was shortly to be explained by the 

 oxygenation theory of Lavoisier. Slight minor modifications of the ap- 

 paratus and method were made by many scientists who appeared almost 

 inordinately 2 occupied in the testing of air in various places. 



Prominent among the users of this instrument was Marsiglio Lan- 

 driani, 3 who in 1775 published a record of his investigation and first in- 

 troduced the term "eudiometer," descriptive of the instrument devised by 

 Fontana. 



In a letter to Priestley, dated at Milan, November 17, 1776, 4 Landriani 

 writes : 



Before you receive this letter I shall have sent you my eudiometer, together with a 

 short memoir, explaining the use of the machine, in order to ascertain with exactness the 

 wholesomeness of the air in any particular place. It is the same instrument that I made 

 use of in my tour through Italy, in the course of which I have had the satisfaction of 

 convincing myself that the air of all those places which, from the long experience of the 

 inhabitants, has been reputed unwholesome, is found to be so, to a very great degree of 

 exactness, by this instrument of mine, so that the theory seems to correspond very well 

 to observation. In the mountains near Pisa I made trial of the air at different heights, 

 beginning on the plain, and proceeding to the highest summits; and found a remarkable 

 difference in the state of the air, every stratum being purer in proportion as I ascended. 



1 Felice Fontana, Descrizioni ed usi di alcuni stromenti per misurar la salubrita dell' 

 aria, Firenze, 1774. 



2 For 20 to 30 years after Priestley's first discovery of the nitric-oxide eudiometer, it 

 would appear from the innumerable references in the literature that every scientist of 

 reputation, and many with no reputation, attempted air-analyses. Writing in 1912, 

 one can but compare proportionally the number of those using the various forms of eu- 

 diometer 130 years ago with those to-day using wireless telegraphic apparatus. Priest- 

 ley has summed up the situation admirably in the following sentences from the preface 

 to volume 3 of his "Experiments and observations on different kinds of air," 1777: 



"Those of my readers who may wish that I would still give a principal attention to 

 this branch of experimental philosophy, will the less regret my discontinuing it, when 

 they are informed with how much ardour and ability these pursuits are now prosecuted 

 in very different parts of Europe. 



"I am also informed by my friend Mr. Magellan, who frequently visits, and has a 

 very extensive correspondence with the Continent, so as to be well acquainted with the 

 present pursuits of philosophers, and who has himself taken pains to instruct many in- 

 genious foreigners in the best methods of making experiments of this kind, that many 

 other persons, whose names are at present unknown to the public, are at this very time 

 assiduously employed on the same subject." 



See also Johann Andreas Scherer, Geschichte der Luftgiiteprufungslehre, Vienna, 

 1785, 2. p. 74. 



3 Marsiglio Landriani, Richerche fisiche intorno alle salubrity dell' aria, Milano, 1775. 



4 Translated and printed in Priestley's Experiments and observations on different 

 kinds of air, 1777, 3, p. 380. 



