APPENDIX 449 



No preliminary treatment of the viscose silk to render it more 

 adsorptive is necessary. 



A 50 per cent alcoholic, alkaline solution of turmeric is prepared 

 by boiling approximately 20 g. of ground turmeric root with 

 50 c.c. of alcohol and adding to the filtered solution an equal 

 volume of water and | to 1 cc. of dilute sodium hydroxide (10 

 per cent). The fibers are immersed in this solution which is 

 then evaporated on a water bath * to a syrupy consistency. The 

 fibers are removed and immediately dipped in 95 per cent 

 alcohol, pressed between filter paper, dipped in a dilute aqueous 

 solution of sulphuric acid, washed with water and dried. The 

 transference of the fibers from the hot dye to the alcohol must 

 be done quickly as otherwise the turmeric adhering to the fibers 

 is removed only with difficulty. Too long an immersion in the 

 alcohol tends to remove the adsorbed dye as well as the excess 

 dye. 



If the fiber still appears to have any unadsorbed turmeric 

 adhering to it (with viscose silk this is easily noted by the lack 

 of luster) it can once more be dipped in alcohol and washed with 

 water. Any unadsorbed turmeric interferes with the formation 

 of the blue color in the boron test. This method as given yields 

 a beautiful golden yellow product which was found to be emi- 

 nently satisfactory. 



Preparation of Wool Impregnated with Zinc Sulphide. - The 

 defatted wool is swelled by soaking over night at room temper- 

 ature, in a 1 per cent solution or sodium hydroxide. It is then 

 washed and dipped 5 or 6 times alternately in solutions of 10 

 per cent zinc acetate and 10 per cent sodium sulphide, pressing 

 out the excess solution but not washing between dippings. 

 After the final dipping, the impregnated wool is washed and 

 dried by pressing between filter paper. Zinc sulphide wool fibers 

 made in this way are sensitive to 0.001 mg. of copper. The 

 sodium sulphide solution should be freshly prepared by passing 

 H 2 S into a solution of NaOH until a portion removed fails to 



1 When preparing or working with fibers impregnated with turmeric all contact 

 with " resistance " glass vessels or object slides is to be avoided since glass of this 

 variety usually contains boron. 



