84 Letters of Acknowledgment from various Societies. 



— when more dilute, brick-red — when still more dilute, greyish, and when 

 extremely dilute, as to.otto) ^ whitish cloud, exactly similar to that which 

 is observed in solutions of arsenious acid after they are kept for some 

 time. 



9th January, 1850. — Mr. Crum in the Chair. 



The Society held a conversational meeting. 



The following were elected members : — Messrs. Alexander Mitchell, 

 Gilbert Lang, Alexander Reid, James Ritchie, Andrew Risk, Laurence 

 Clark, John Cuthbertson. 



23d January, 1 850. — Tlie Vice-President in the Clmir. 



The following were elected members: — Dr. James Steven, Messrs. 

 James Robert Napier, Charles Thorburn, James M'Kenna, James Graham, 

 Thomas Ferguson, John Burnett, George M'Callum. 



Letters were read from the Royal Society of London, Royal Institu- 

 tion, Liverpool Literary and Philosophical Society, acknowledging receipt 

 of Vol. 3d, Part 1st of Proceedings of the Society. 



The Librarian intimated that Robert Blackie, Esq., had presented to 

 the Philosophical Society's Library a copy of the Imperial Dictionary, in 

 2 vols., recently published by the Messrs. Blackie, and moved the thanks 

 of the Society, which were unanimously given. 



Mr. Stein exhibited and described a machine invented by him for 

 checking the charge of duty upon spirits. A communication was made 

 by Dr. R. D. Thomson, of a simple and continuous method of washing 

 filters, by Mr. Eustace Gary Summers, which has been published in the 

 Philosophical Magazine, vol. 35, p. 96. 



Qth February, 1850. — TJie President in the Cliair. 



The following were elected members : — Messrs. David Wilson, George 

 Simpson, James Manson, John Blackie, jun., John Neilson. 



Letters acknowledging receipt of Proceedings were read from Royal 

 Institution, Liverpool, and the Literary and Philosophical Society of 

 Manchester. 



Dr. R. D. Thomson communicated an account of his experiments on 

 the Fluids of Cholera, and on the atmosphere in December, 1848, and 

 January, 1849, which have been published in the Transactions of the 

 Royal Medical and Chirurgical Society of London, for 1850. 



