776 REPORT— 1898. 



smell to be just observable was reduced frona a few minutes or seconds when the 

 tube was filled with air to less than half a second for a {^ood vacuum ; with solid 

 camphor it was reduced from twenty minutes to one second ; and, when moist rose 

 leaves were used, from fifty minutes to two seconds. But with solid particles of 

 musk the time was not reduced below twenty minutes by taking away the air; 

 while with dried lavender flowers and dried woodruff leaves no smell could be 

 detected after the two limbs had been connected for many hours, and a good 

 vacuum maintained. These experiments are, of course, somewhat complicated by 

 variations in the amount of odorous surface exposed, but they seem to indicate 

 that with these particular dried substances either the rate of evolution of the 

 ficent, or its rate of propagation, or both, are very slow even in a good vacuum. 



I have also carried out some tests on the power of different substances to 

 absorb various scents from the air. Lard, it is well known, is used to absorb the 

 perfume from flowei-s in the commercial manufacture of scents, perhaps because it 

 has little odour of its own, and because the scent can be easily distilled from it. 

 But if lard, wool, linen, blotting-paper, sillc, &c., be shut up for some hours in a 

 box at equal distances from jasmine flowers, dried woodrufl' leaves, or from a 

 solution of ammonia, I find that it is not the lard, but the blotting-paper, that 

 smells most strongly when the articles are removed from the box. On the other 

 hand, when solid natural musk is employed, it is the wool that alone acquires 

 much smell, even after the box has been shut up for days. 



Another noteworthy fact is the comparatively rapid rate at which grains of 

 natural musk are found to lose their fragrance when exposed to the air. The 

 popular statement, therefore, that a grain of musk will scent a room for years 

 supplies but another example of the contrast between text-book information and 

 laboratory experience. 



The power of a smell to cling to a substance seems to depend neither on the 

 intensity of the smell nor on the ease with which it travels through a closed 

 space. Musk has but a faint smell, but the recollection of the greeting of a rich 

 Oriental survives many washings of the hands. The smell of rose leaves, again, is 

 but faint, and it travels very slowly through air in a tube ; and yet the experi- 

 ments on its propagation in the glass vacuum apparatus were rendered extremely 

 troublesome by the difiiculty experienced in removing the traces of the smell from 

 the glass between the successive tests. Eubbing its surface was quite ineflectual, 

 and even the mercury had to be occasionally shaken up with alcohol to free it 

 from the remanent smell. In fact, we fotind, as Moore put it : 



' You may break, you may shatter the vase if you will, 

 But the scent of the roses will cling to it still.' 



This absor])tion of scents by glass, and the ease with wbicli I found that jasmine 

 flowers could be distinguished from woodruff leaves, even when each was enclosed 

 in a series of three envelopes specially prepared from glazed paper, and when many 

 precautions were taken to prevent an odour being given to any of the envelopes 

 in the operation of closing, as well as to prevent its diffusion through the joins in 

 the paper, led me to try whether an actual transpiration through glass could be 

 detected with the nose. For this object a number of extremely thin glass bulbs 

 were blown from soda and from lead glass, so thin that they exhibited colours like 

 a soap babble, and felt, when gently touched, like very thin oiled silk, and after a 

 little ammoniated lavender, amyl nitrite, ethyl sulphide, mercaptan, solution of 

 musk, oil of peppermint, and propylamine had been introduced into them respec- 

 tively, they were hermetically sealed, and placed separately in glass stoppered 

 bottles. 



In some cases, on removing the stopper from a bottle after many hours, a faint 

 odour could be detected, but so, generally, could a minute flaw after much searching ; 

 the crack, however, being so slight that it did not allow sufficient passage of the 

 air to prevent the bulb subsequently breaking, presumably from changes of atmo- 

 spheric pressure. And in those cases where a smell was detected without any 

 flaw being found in the glass, the subsequent breaking of the bulb put an end to 

 further testing. The question, therefore, remains unanswered. 



