130 Notice respecting some Experhnents on Alcohol. 



nianner become perfectly limpid, retaining uninjured their 

 smell and taste. 



In a similar manner the acid residuum from the prepara- 

 tion of sulphuric ether may be perfectly deprived of colour. 

 The residuum, mixed with an equal weight of water, is 

 filtered through paper (placed in a glass tunnel and sup- 

 ported by a small piece of cloth placed in the neck) to se- 

 parate the carbonaceous and oily matter forn)ed by the 

 action of the acid upon the alcohol. If 30 grammes of 

 bone black be mixed with a litre of the filtered acid, in a 

 matrass, agitated from time to time, at the end of two or 

 three days, on filtering the mixture, the acid will pass 

 through perfectly colourless. By t,his means almost the 

 ■whole of the acid employed in the preparation oPether may 

 be recovered, and the acid (when evaporated to drive oft' the 

 water) may be employed for any use to which sulphuric 

 acid is applied. 



Tincture of turnsole, mixed with a small quantity of ani- 

 mal charcoal, speedly loses its colour. 



The charcoal is prepared as follows : Fill a crucible with 

 the most compact parts of ox and sheep bones; lute the 

 cover carefully, leaving only a small opening at the top; 

 place the crucible on a forge fire, and heat it gradually till 

 red : when the flame from the oily and gelatinous parts of 

 the bones has ceased, diminish the opening and suddenly 

 raise the fire : — carburctted hydrogen gas and oxycarburet 

 •will then be evolved. When cold reduce the charcoal, on 

 porphyry, to a fine powder. 



Ivory black possesses the same property as bone black. 

 In a word, all charcoals prepared from animal substances 

 by calcination in close vessels, answer for this purpose. 



XXr. Notice respecting some Experiments on Alcohol; 

 read before the Edinbtirgh Insiitule 2d February 1813. 

 By Mr. HuTTON. 



X HAVE been prevailed upon to communicate a notice of 

 some experiments and observations I have made on the 

 production of a ureat degree of cold. It is scarcely neces- 

 sary to observe, that my doing so at this time is n6t a mat- 

 ter of choice: these experiments and observations were 

 mentioned to my friends ; and they were made without any 

 injunction as to secrecy, as I did not anticipate that such 

 communications would cither be received with so much 

 Avidity, or repeated with so much eagerness. The conse- 



tjuence 



