568 SEC. 13. - CHEMISTRY. 



2406. Original Tubes containing Gases liquefied by 



Faraday. The Royal Institution of Great Britain. 



\.~\ 12. Arseniuretted Hydrogen. 



2. ) 13. Ammonia. 



8. V Muriatic Acid. 14. j Hydrobromic AckL 



5.J 16. Chlorine. 



} 



ch,o rin eanaSu,p,, Acid. 



8. Sulphurous Acid. 19. Sulphuretted Hydrogen. 



9. 1 ^ 20. Hydriodic Acid. 



10. /Cyanogen. ^ A ;! seniuretted Hydrogen. 



11. Ammonia. 



(Phil. Trans. 1845.) 



687c. Faraday's Laboratory Note Book. 



The Royal Institution of Great Britain. 



Faraday's record of his condensation and liquefaction of gases, March 19, 

 1823. 



Apparatus used by Brande for the continuous pre- 

 paration of Ether. 



The Royal Institution of Great Britain. 



2409a. Original Apparatus, by M. Dumas, for ascertaining 

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



2409b. Apparatus, by M. Dumas, for ascertaining the 

 density of vapours. M. J. Dumas, Paris. 



APPARATUS EMPLOYED BY THE LATE THOMAS GRAHAM, F.R.S., 

 MASTER OF THE MINT, IN HIS PRINCIPAL RESEARCHES BETWEEN 

 THE YEARS 1834 AND 1866. The series is interesting as showing 

 the simplicity of the appliances with which Graham worked, and 

 by the aid of which he discovered facts and established laws which 

 have since proved to be of so much importance. 



W. Chandler Roberts, F.R.S. 



2539. Tubes with discs of graphite and hydrophane employed 

 by Graham in experiments on " diffusion " of gases. 



These experiments were commenced in 1834, when the discs were formed 

 of plaster of Paris. The instrument consists of a graduated glass tube, open 

 at one end and closed at the other by the porous substance. When such a 

 diffusion tube is filled with a gas over mercury an interchange of the gas 

 and the air takes place through the porous septum. By experiments such as 

 these Graham determined the diffusion rates of different gases, and developed 

 the law that their diffusibilities vary in the inverse ratio of the square roots 

 of their densities. 



2540. The Apparatus employed for ascertaining the diffusion 

 rates of liquids (Bakerian Lecture, 1849). 



The saline solution to be diffused was placed in the inner vessel, which 

 communicated freely with distilled water in the outer vessel. It was shown 

 by this means that, when two liquids of different density and capable of mix- 

 ing are placed in contact, diffusion takes place between them, much in the 



