24 DR. II. A. BAYNE ON THE ANALYSIS OF SILK. 



From the above analytical re.siilts it would thus seem that, lor separations oi' a mixture 

 of silk and wool, the use of cold concentrated hydrochloric acid or of basic zinc chloride 

 yields the most reliable results ; while for separation of silk from cotton or linen the 

 ammoniacal oxide of nickel, and more particularly the alkaline glycerine solution of oxide 

 of copper, yield thoroughly tnxstworthy indications. When the liability to loss of small 

 portions of fibre incidental to analyses of this kind (in the various treatments and wash- 

 ings to which the cloth is submitted) is considered, the small percentage of loss on wool 

 in the former reagents, and of cotton and linen in the latter, entitles the methods to be 

 deemed of considerable exactitude. 



The results of attempts at determining the amount of .^ilk quantitatiA'ely.by repre- 

 cipitation from any one of its solvents were unsatisfactory. While the fibroin is in part 

 often precipitated, the serecine seems to be too readily soluble to be wholly precipitable. 

 Lidow's statement that fibroin is wholly precipitable from its solution in melted oxalic 

 acid by 96% alcohol, I do not find to be substantiated on experiment, nor that from its 

 solution in tartaric, gallic, pyrogallic, citric acid it is wholly precipitable by tannic acid 

 or saturated saline solutions. The precipitation of silk from solution in alkaline glycerine 

 solution of oxide of copper and from other solvents by neutralization of the liquid, seemed 

 only partial and not such as to aflPord a quantitative method. 



