296 Presents. [Jan. 31, 



nre well seen also in the indium spectrum No. 5 from 3850 to 3514*1. 

 The enlargements of these prismatic spectra, however, cannot com- 

 pare with the grating spectra, the air lines being, as far as possible, 

 suppressed in the former. 



I do not attribute much importance to the fact that argon gives 

 two spectra ; the red appears to be the spectrum of the first order, or 

 the spectrum of the lower temperature which corresponds thereto ; 

 the blue is the line spectrum, or spectrum at the higher tem- 

 perature. 



I have photographed simultaneously from the same spark the two 

 spectra of nitrogen as rendered by atmospheric air. 



It is therefore more likely that argon is one substance and not two. 

 Whether it is a compound or an element is a question into which the 

 following considerations may enter. There are at present no"gaseous 

 substances known which can withstand the temperature of the 

 condensed spark without exhibiting the spectra of one or other of the 

 elements of which it is composed. If, therefore, argon were N 3 it 

 would disclose the spectrum of nitrogen. As the spectrum is not 

 that of any known substance, it follows that, if a compound, it must 

 be a compound of a new element. 



A Letter from Prof. FITZGERALD upon the Atomicity of Argon was 

 read. 



Presents, January 31, 1895. 



Transactions. 



Brussels : Association Beige des Chimistes. Bulletin. Annee 



VII. No. 8. 8vo. Bruxelles 1893. The Association. 



Bucharest: Societatii de Sciinte Fizice. Buletinul. Anul III. 



Nos. 58. Centenarul lui Lavoisier, 1794-1894. 4to. 



Bucuresci 1895. The Society. 



Cracow : Academie des Sciences. Bulletin International. De- 



cembre. 8vo. Cracovie 1894. The Academy- 



Edinburgh : Royal Scottish Society of Arts. Transactions. Vol. 



XIII. Part 4. 8vo. Edinburgh 1894. The Society. 



Royal Society. List of Members. 1894. 4to. [Edinburgh.'] 



The Society. 

 Gottingen : Konigl. Gesell. der Wissenschaften. Nachrichten. 



1894. No. 4. 8vo. Gottingen 1895. The Society. 



Heidelberg : Naturhistorisch-Medicinscher Verein. Verhand- 



lungen. Neue Folge. Band 5. Heft 3. 8vo. Heidelberg 



1894. The Society. 



