86 Dr Stark on the Iivfluence of Colour on Odours. 



a body may suffer by parting with a great store of effluvia 

 And, 5. The great quantity of space that may be filled, as to 

 sense, by a small quantity of matter, when rarified or dispersed.'"' 

 In illustration of these divisions of his subject, Mr Boyle in- 

 stances the extreme extensibility of gold ; and the expansion of 

 half a grain of gunpowder, which, when exploded, filled a space 

 500,000 times greater the powder. The dissolution of a grain 

 of copper in sal-ammoniac is still more surprising, communicat- 

 ing a tincture to 28,534 its weight of water ; a single grain gave 

 a blueness to above 256,806 pints of limpid water, and even a 

 perceptible colour to double that quantity.* 



The results of these experiments with gold, gunpowder, and 

 the colouring matter of dissolved copper, seem to be stated for 

 the purpose of gaining credence as to the still more wonderful 

 dissemination of the particles of odorous bodies. As Mr Boyle's 

 experiments on odours or effluviums are, however, at the dis- 

 tance of nearly two hundred years, the only one which have been 

 made, I give the details in his own words : — 



" Having, for curiosity sake, suspended in a pair of exact 

 scales, that would turn with a very small part of a grain, a piece of 

 ambergris bigger than a walnut, and weighing betwixt an hundred 

 and six score grains, I could not, in three days and ahalf thati had 

 opportunity to make the trial, discover, even upon that balance, 

 any decrement of weight in the ambergris, though so rich a per- 

 fume, lying in the open air, was like in that time to have parted 

 with good store of odoriferous steams. And a while after, sus- 

 pending a lump of assafcetida five days and a half, I found it 

 not to have sustained any discernible loss of weight, though, in 

 spite of the unfavourable cold weather, it had about it a neigh- 

 bouring atmosphere, replenished with fetid exhalations. And 

 when, twelve or fourteen hours after, perhaps upon some change 

 of weather, I came to look upon it, though I found that in that 

 time the equilibrium was somewhat altered, yet the whole lump 

 had not lost a quarter of a grain, which induced me to think 

 that there may be steams discernible even by our nostrils, that 

 are far more subtile than the odorous exhalations of spices them- 

 selves.*" -f- 



• Boyle*8 Works, vol. iii. p. 661, 668. f Ibid. p. 672, 67:i. 



