44 ABSORPTION OF RADIANT HEAT PARTI. 



of measurement. This result induced Professor Tyndall 

 to believe that ozone is produced by the packing of the 

 atoms of elementary oxygen into oscillatory groups ; and 

 that heating dissolves the bond of union and allows the 

 atoms to swing singly, thus disqualifying them from 

 either intercepting or generating the motion which as 

 systems they were competent to intercept and generate. 

 The indefinitely small and invisible constituents of 

 perfumes of plants and flowers ^are proved to be com- 

 pound bodies by their absorptive and radiating proper- 

 ties. The dried leaves of a flower or aromatic plant such 

 as thyme were stuffed into a glass tube 18 inches long 

 and a quarter of an inch in diameter. It was then 

 inserted between the drying pipe of the machine and 

 the experimental glass tube, which was exhausted, and 

 the needle of the goniometer stood at zero. Then when 

 the air admitted into the drying pipe passed over the 

 thyme and carried its aroma into the experimental tube, 

 the needle was deflected, and from thence the absorption 

 of the thyme was computed to be 33 times greater than 

 that of the air which carried it. By the same process 

 it was found that the absorption of peppermint was 34 

 times, spearmint 38 times, lavender 32 times, and worm- 

 wood 41 times greater than that of the dry air, which 

 was unity as usual. When small equal squares of bibu- 

 lous paper rolled into cylinders and moistened with an 

 aromatic oil, were substituted for the dried herbs, the 

 absorption corresponding to the deflection of the needle 

 was for dry air, equal to 1, 



Patchouli 

 Sandal wood 

 Geranium 

 Oil of cloves . 

 Otto of roses 

 Bergamot 

 Lavender 

 Lemon . 



30 



32 



33 



33-5 



36-5 



44 



60 



67 



Orange 67 



Thyme . . . -. .68 



Rosemary * . . . .74 



Oil of laurel . . . .80 



Chamomile flowers . . .87 



Spikenard . . . .355 



Anise seed . 372 



