I. - RESEARCH. 477 



2402. Flattner's Diamond Mortar, in steel. 

 No. 1, with brass capsule. 



No. 2, without" 



No. 3, A. Herbst, Berlin. 



2403. Preyberg's Diamond Mortar, in steel. 

 No. 1, with brass capsule. 



No. 2, without 



No. 3, A. Herbst, Berlin. 



2405. Faraday's Apparatus for the Condensation and 

 Liquefaction of Gases. 



The Royal Institution of Great Britain. 



Apparatus used by Faraday for the condensation and liquefaction of gases, 

 consisting of condensing pump and connexions, conducting and other tubes, 

 gauges, sealed tubes for containing the liquefied gases, &c. &c. Phil. Trans. 

 1845. 



2406. Original Tubes containing Gases liquefied by 

 Faraday. The Royal Institution of Great Britain. 



1.1 12. Arseniuretted Hydrogen. 



2. ] 13. Ammonia. 



8. j. Muriatic Acid. 14. j Hydrobromic Aci(L 



5.J 16. Chlorine. 



8. Sulphurous Acid. 19. Sulphuretted Hydrogen. 



9. 1 20. Hydriodic Acid. 



10. } C y an g en - 21. Arseniuretted Hydrogen. 



1 1 . Ammonia. 



(Phil. Trans. 1845.) 



2407. Apparatus by which Dr. Andrews and Professor Tait 

 proved that ozone is a condensed form of oxygen. 



Dr. Andrews, F.R.S. 



Dry oxygen gas is exposed to the action of the silent electrical discharge in 

 a glass tube terminating in a U tube containing sulphuric acid, which indicates 

 by its change of position the change of volume in the gas. 



2408. Apparatus for exhibiting in the lecture room the con- 

 traction which takes place when oxygen is changed into ozone. 

 It is formed of a modified Siemen's tube : the contraction being 

 shown by the ascent of the sulphuric acid in which the open end 

 of the tube is immersed. Dr. Andrews, F.R.S. 



2409. Apparatus used for ascertaining the Density of 

 Ozone. Mr. J. Louis Soret, Geneva. 



This process, based upon the velocity of diffusion, has been described in 

 detail in the " Recherches sur le Densite de TOzone " (Archives des Sciences 

 physiques et naturelles, 1867, Vol. 30, p. 328. Annales do Chimie et de 

 physique, 1868, Vol. 13, p. 264). Constructed by the Geneva Association 

 for the Construction of Scientific Instruments. 



24O9a. Original Apparatus, by M. Dumas, for ascertaining 



the density of gases. M. J. Dumas, Paris. 



