﻿332 Transactions — Chemistry, 



Art. LIX. — Ahsorjytion of Gopper from its Atnmoniacal Solution by Cellulose 

 in presence of Caustic Potash. By W. Skey, Analyst to tlie Geological 

 Survey of New Zealand. 



[Read before the Wellington Philosophical Society, 25th November, 1871.] 



When a weak ammoniacal solution of copper containing a little caustic potash, 

 is |)oured upon a filter of Swedish paper (cellulose) the liquid which passes 

 through the paper is quite or nearly colourless, and the filter is found to have 

 retained all, or neai-ly all, the copper of such solution. 



The form in which the metal is retained appears to be that of a greenish 

 blue hydrate, this being in weak chemical combination with the cellulose of 

 the filter associated with a little ammonia. 



A solution similar to the above, except that cobalt is substituted for copper, 

 is unafiected by cellulose. A nickel solution could not well be applied, as the 

 potash rapidly precipitates the metal unaided. 



The presence of tartaric acid, sugar, or albuminous matters, does not 

 interfere in any way with the absorption of copper instanced, nor are any 

 of these substances adequate to supply the part of ammonia in the absorp- 

 tion stated. 



In testing liquids, therefore, for diabetes, etc., we may, by the use of filter 

 paper in the manner indicated, remove any ammonia that may happen to be 

 present in such solutions, by which we are enabled to be certain that any 

 blueness of colour they may possess after such treatment is not due to the 

 presence of an ammoniacal compound of copper. 



