2 8o ROUND THE YEAR 



concluded that the cavities were separate and air- 

 tight. 



The long flotation of Alder-nuts on water suggested 

 that they contained some 

 resinous or other water- 

 repelling substance. Dr. J. 

 B. Cohen, of the Yorkshire 

 College, was good enough 

 to examine them for me. 

 He says : " About 4^ 

 grams of Alder seeds were 

 dried in a steam-oven and 

 extracted with ether. They 

 lost in the first process 17-1 

 per cent, of water, and in 

 the second 2-4 per cent, of 

 extractive matter. The sub- 

 stance extracted formed a 

 perfectly solid and brittle, 

 light-yellow mass. It gave 

 none of the reactions for 

 resin, but on heating melted 

 and evolved a smell closely 

 resembling that of hot lin- 

 seed soil. The seeds freed 

 from oil floated on water, 



FIG. 68-Section through Alder-nut, *>Ut SOme of them Sank 



*Z&S^Stt after a time. The majority, 

 however, floated after four 



days' soaking. On the other hand, when the seeds 

 freed from oil were cut in halves, and soaked 

 in water, and the air then extracted by exhaust- 



