388 On a Mineral containing Benzoic Acid. 



Examination of this Substance. 



Specific gravity less than water. 



2000 grains of distilled water at 60° Fahrenheit dissolve 

 three grains of this substance ; alcohol of specific gravity 82, 

 at 60^ Fahrenheit, dissolves a considerable quantity of it, and 

 forms a red tincture. 



Water decomposes this tincture and precipitates resin. It 

 has not any tannin. 



Benzoic acid may be obtained from it by sublimation. This 

 substance consists of altered resin, benzoic acid, and earth, and 

 appears to be produced by the decay and carbonization of 

 Some tree containing benzoin, of which there are many in 

 Colombia. It is used by the natives medicinally as a styptic 

 or astringent. In this particular the Indians follow the Per- 

 sians, in the country of which people a similar substance exists, 

 and is so highly prized for its medical virtues, as to become 

 royal property. Murindd resembles, in many respects, this 

 bituminous earth from Persia. 



On the Mechanism of the Act of Vomiting. By MarshalIj 

 Hall, M.D., F.R.S.E., &c. &c. 



Two opinions have divided physiologists respecting the nature 

 of the act of vomiting. It was originally and long thought 

 that this act consisted simply in a sudden and forcible con- 

 traction of the stomach itself Afterwards Bayle, and Chirac, 

 and more recently M. Majendie, considered that the stomach 

 is inactive, and evacuated by being subjected to pressure by 

 the simultaneous contraction of the diaphragm and abdominal 

 muscles. 



It appears to me that neither of these opinions is correct. 

 M. Majendie distinctly proves by actual observation, and by the 

 substitution of a bladder in the place of the stomach, that the 

 contraction of this organ is not usually subservient or necessary 

 to the act of vomiting. I refer to the interesting paper -^ of 

 that eminent physiologist for the more full elucidation of this 

 first question. I proceed to state such observations as appear 

 to me to controvert the second, and to establish that view of 

 this subject which I have myself been led to adopt. 



♦ Memoire sur le Vomissement^ par M. Majendie. A Paris, 1813. 



