1823.] Scientific Intelligence, 73 



ing the solution, a further quantity was obtained ; when after this, the 

 solution was evaporated to dryness, no purpuric acid was obtained ; 

 but, on the contrary, if the solution in nitric acid be immediately eva- 

 porated to dryness, purpuric acid is formed. 



The excrement of the boa contains ammonia, and in so great excess 

 that it may be considered as a suburate of ammonia ; when distilled 

 with a weak solution of potash, water containing ammonia is condensed 

 in the receiver; when the experiment was repeated with uric acid, no 

 ammonia was obtained. When the excrement is burnt, the ashes are 

 found to contain oxide of iron and carbonate of lime, but no phosphate 

 of lime.— ( Schweigger*s Journal.) 



XVI. Heliotrope, 

 According to Dr. Brandes and Firnhaber, the heliotrope is com- 

 posed of 



Silica 96'25 



Protoxide of iron 1*25 



Alumina 0'86 



Water 105 



99'4<1 



It, therefore, resembles chalcedony on silica being slightly mixed 

 with other bodies. — (Ibid.) 



XVI. Carhonate of Magnesia and Iron, Sfc. 



Prof. Walmstadt, of Upsal, has analysed carbonate of magnesia from 

 Hartz containing the carbonates of iron and manganese. The texture 

 of this mineral is foliated, and its primary form is a rhomboid of 

 108° 1.7, differing of course still more from calcareous spar than rhomb 

 spar. The results of the analysis were : 



Carbonate of magnesia 84*36 



Carbonate of iron 10*02 



Carbonate of manganese 3*19 



Silica 0-30 



Water 051 



Loss, and a substance destructible 



by lire.. 1-62 



10000 



(Ibid.) 



XVII. On the Absence of Carbonic Acid in the Atmosphere over the Sea 



M. Vogel found that atmospheric air taken over the sea half a mile 

 from the sea-shore off Doberan, contained so little carbonic acid, that 

 a solution of pure barytes was hardly made turbid by it ; while the 

 same bulk of air taken on shore produced a considerable quantity of 

 carbonate of barytes. 



M. Vogel repeated these experiments In 1822 in the Channel, two 

 leagues from Dieppe, Avhere he emptied a large bottle wilh distilled 

 water, and tried the air afterwards with a solution of pure barytes, which 

 became so little turbid that it hardly could be perceived ; when the ex- 

 periment was repeatedon shore, thesolution of barytesbecame extremely 



