20 Ol'servatiojis on the Measurement of 



quantity of acetic acid may be formed, and the latter may 

 have acted on the carbonate of magnesia left in the liquor, 

 on account of its solubility being greater than that of the 

 carbonate of lime. 



We generally ascertain by the colour, smell and taste, 

 and above all by the property wiiich llie urine of the beaver 

 pos.sejses of staining alumed cloths, the kind of vegetables 

 on which the animal feeds. 



In the urine of die animal \\h;ch I made the subject of 

 nn' experiment, I dls!iugui^hcd evident marks of the co- 

 louring matter of willow bark, and its keeper conliinied 

 the observation. 



There seem to be cases, therefore, in which certain vege- 

 table substances n)ay pass through the diirestive organs, 

 and the circulation, without entirely losing the properties 

 ■which distinguish lijem in their natural state. 



I also found in the urine of the beaver a quantity of 

 iron, which at first astonished me ; but having reflected 

 that it had been collected in a tinned iron vessel, and that 

 it contained carbonic acid, I thought that the greater quan- 

 tity of this metal proceeded from the vessel. 



The urine of the beaver is therefore composed ofj 



1. Urea. 



2. Animal mucus. 



3. Benzoaie of potash. 



4. Carbonate of lime and magnesia. 



5. Acetate of magnesia (doubtful). 



6. Sulphate of potash. 



7. Muriate of potash or of soda. 



8. Vegetable colouring maiter. 



9. Lastly, a little iron. 



VI. Observations on the Measurement of three Degrees of 

 the Meridian conducted in England, by Lieut. -Colonel 

 William Mudge. By Don Joseph Rodriguez. 

 Cormmmicated by Joseph de Mendoza Rios, Esq. 

 F.R.S* 



A. HE determination of the figure and magnitude of the 

 earth has ai all tinies excited the curiosity of mankind, and 

 the history of the several attempts made by astronomers to 

 solve this problem might be traced to the most remote an- 

 tiquity. But the details of the methods pursued by the 

 ancients on this subject being extremely vague, and their 



• From tlie Philosopliical Transiiotions for 1812, part ii. 



results 



