344 Col. Beaiifoy's Astronomical Observations. [May, 



Article V. 



Astronomical Observations, 1823. 

 By Col. Beaufoy, FRS. 



Bushei/ Heath, near Stanmore. 



Latitude 51° 31' 44'3" North. Longitude West in time 1' 20-93". 



Mar. 30. Emersion of n Scorpio from the (,.■. .n .„./.>, m- . -r, , 



moon r j 12n 54' 16-4" Mean Time at Bushey. 



April 12, Emersion of Jupiter's first J 8 53 55 Mean Time at Bushey. 



satellite I 8 55 16 Mean Time at Greenwich. 



Article VI. 



On the Ultimate Analysis of Vegetable and Animal Substances. 

 By Andrew Ure, MD. FRS * 



The following is an account of Dr. Ure's process and 

 apparatus for the ultimate analysis of vegetable and animal 

 compounds, as described in this paper. The French chemists 

 who have operated most with peroxide of copper in the analysis 

 of organic substances, being aware of its quick absorption of 

 humidity from the atmosphere, direct it to be used immediately 

 after ignition, and to be triturated with the organic matter in a 

 hot mortar of agate or of glass. " Yet this precaution," Dr. Ure 

 observes, " will not entirely prevent the fallacy arising from the 

 hygrometric action ; for I 'find that peroxide thus treated does 

 absorb, during the long trituration essential to the process, a 

 certain quantity of moisture, which, if not taken into account, 

 will produce serious errors in the analytical results. It is better, 

 therefore, to leave the powdered peroxide intended for research, 

 exposed for such time to the air, as to bring it to hygrometric 

 repose, then to put it up in a phial, and by igniting 100 grains 

 of it in a proper glass tube, sealed at one end, and loosely 

 closed with a glass plug at the other, to determine the propor- 

 tion of moisture which it contains. This, then, indicates the 

 constant quantity to be deducted from the loss of weight which 

 the peroxide suffers in the course of the experiment. The mortar 

 should be perfectly dry, but not warm." 



" Experimenters have been at great pains to bring the various 

 organic objects of research to a state of thorough desiccation 

 before mixing them with the peroxide of copper ; but this prac- 



• Abstracted from the Philosophical Transactions for 1822. Part II. 



