Dr Stark on the Influence of' Colmir on Odours. 87 



Keill, in his Introduction to Natural Philosophy, founding 

 upon these experiments of Mr Boyle, makes a calculation of the 

 number of odorous particles, which may thus be in a sphere of 

 five feet radius. He supposes that there is but one particle of 

 the odorous body in every part of that space, which part is equal 

 to the fourth of a cubic inch ; and though it is probable that 

 effluvia so rare would scarcely, if at all, affect the sense of smell, 

 yet upon this principle he calculates that in a sphere of the semi- 

 diameter of five feet there wilt be 57,839,616 such spaces, and 

 of course just so many odorous particles.* 



In Mr Boyle's experiment with assafoetida, the mass exposed 

 to the air lost, in six days, the eighth part of a grain in weight ; 

 but since the flux of effluvia from an odoriferous body is conti- 

 nual, it is manifest it ought to be proportionate to the time ; and 

 therefore, in one minute'*s time, the weight of the effluvia flow- 

 ing from the assafoetida would be equal to ^gijo ^^ ^ grain, and 

 the magnitude of the particles equal tOj^gg^jjg^lo^cjjoooo 

 parts of a cubic inch.-|- 



Haller,! for more than forty years, preserved 400 disserta- 

 tions, of forty pages each, which a single grain of ambergris had 

 perfumed, and at the end of that period they had lost nothing 

 of their odour. This learned physiologist has calculated that 

 each inch of the surface of the papers had been impregnated 

 with j^gi^V?oo?^ ^^ ^ grain. The surface of the paper was es- 

 timated at 8000 feet, and it lay in a bed of air at least one foot 

 thick for 14,600 days. Mr Boyle also mentions his having a 

 pair of Spanish perfumed gloves which preserved their odour 

 for nearly thirty years. § 



Mr Boyle further remarks, in proof of the prodigious diffli- 

 sion of odorous effluvia through vast tracts of air, that a friend 

 of his sailing along the coast of Ceylon for almost a whole day, 

 at the distance of twenty or twenty-five miles, the wind blowing 

 from the shore, felt the air " manifestly odoriferous."* || Lord 

 Valentia, a late traveller, remarks of the same island, that at 

 nine leagues distance, the aromatic odour of the spices was dis- 



• Keill's Introduction to Natural Philosophy, p. 48, 49. Lond. 1758. 



t Ibid. p. 49, 60. 



X Elementa Physiologiae, torn. v. p. 157. I^ausannse, 1769, 4to. 



§ Boyle's Works, voL iii. p. 677- li Ibid. voL iii p. 677. . 



