used the disks and wire may be of nickel instead of platinum. A few 

 platinum disks may be kept on hand and used when the nature of the 

 solvent requires it. (2) The sample after being extracted with ether 

 can be much more readily transferred to the crude fiber flask by 

 merely using a glass tube small enough to enter the constricted por- 

 tion of the extraction tube easily, and pushing out the disk, asbestos 

 mat, and sample. The wire attached to the disk should enter the small 

 glass tube. In most cases this operation takes the sample out clean, 

 .but it is very easy to wash out any particles that may adhere to the 

 sides. (3) Many tubes of the old form were defective and not able 

 to stand the vacuum pressure, the disk being drawn into the bulb. An- 

 other source of loss was the breakage caused by heating to dry the 

 asbestos felt, a large percentage of tubes developing cracks from the 

 strains due to the projections D (fig. 1). The tubes here described, 

 when broken, can be replaced for a few cents and the disks will last 

 for } r ears. 



The price of the old tubes is about $1.30 each, while the new form, 

 with the disk, will cost probably about 10 cents. These modified 

 flasks and tubes have been used in this laboratory for some time and 

 have proved much more satisfactory than the regular form. 



Approved: ' 

 JAMES WILSON, 



Secretary of Agriculture. 



[Cir. 69] 



O 



