22 DR H. A. BAYNE ON 



stantiated by experiment. The result of several experiments with this reagent gave a loss 

 of from 15 to 30% on the amount of wool, and from 2 to 3.5% on the vegetable fibre 

 ployed. 

 Among concentrated acids, the only one yielding satisfactory results was found to be 

 hydrochloric acid. Cold concentrated hydrochloric acid of 1.19 sp. gravity dissolved silk 

 in from fifteen to twenty minutes, with a loss of woollen fibre amounting to only 0-83%. 

 1.12 acid acted likewise with a loss of OYl% on wool, while cotton and linen were much 

 more largely affected. This reagent may, therefore, be employed as a method of separating 

 with considerable exactitude silk from wool but not from vegetable fibre. 



Action of Alkaline Solutions. — Caustic potash and soda dissolve silk and also 



wool ; even where these reagents are dilute. They also affect, when dilute, cotton and 



linen fibre to a small extent. Thus seven analyses with 4% caustic soda, heated to incipient 



boiling for from five to ten minutes, yielded the following average results : — 



Silk and Wool completely dissolved. 



Cotton fibre, loss of. 1 . 12%. 



Linen, " 2.01%. 



Special Reagents. 



Ammoniacal Oxide of Nickel.— This reagent has been proposed as a solvent for silk 

 by Schlossberger (Annalen der Chemie and Pharmacie, Vol. CYII. p. 21.) It was prepared for 

 these analyses by precipitating the hydrated oxide of nickel by an alkali, separating the 

 precipitate from the lic]uid, washing and dissolving in concentrated ammonia. This 

 reagent dissolves silk at ordinary temperature in two to three hours, but also affects other 

 fibres to a small extent. Wool becomes of a brown colour, removable by dilute hydro- 

 chloric acid. Cotton and linen seemed very little affected by this reagent. 



Average of four analyses : — 



Silk wholly dissolved. 



Wool, loss of 4 . 10%. 



Cotton, " 0.5.5%. 



Linen, " 0.52%. 



Ammoniacal Oxide of Coppee. — The so-called Schweizer reagent {Dingler's Poly- 

 technkhes Journal, Vol. CXLVI. p. 361,) prepared by dissolving basic cupric sulphate in con- 

 centrated ammonia, dissolves silk readily, but also affects wool, cotton, and linen, though 

 more slowly. 



Two analyses in which the cloth was removed from the liquid immediately upon 

 solution of the silk (about twenty minutes) yielded the following average results : — 



Wool, loss of 2 .86%. 



Cotton, " 2.84%. 



Linen. " 7.31%. 



Alkaline Glycerine Solution of Oxide of Copper. — Loewe (Ding'ler's Pohjlech- 

 nirhes Journal, Vol. CCXXII. p. 274,) recommends for the preparation of this reagent the 

 following proportions : — 



Cuprio Sulphate 16 grs. pure. 



Distilled Water 140 tol60 c.c. 



Glycerine 8 tolO grs. of 1 . 24 den.'ïity. 



