384 Transactions. — Chemistry. 



ensues, then place it in a horizontal position over ammonia- 

 vapour. The gold-oxide precipitates, and can all be evenly 

 reduced in the paper by warm oxalic acid. Test-paper so 

 produced has a regular and easily-perceptible purple or red 

 tinge, and contains about ^hs of a grain per square inch. 

 Paper containing rtshns per inch, or Tnir^rtrTT of a grain of gold 

 on iV of an inch square, has a very faint tinge ; but, still, 

 this can be discerned upon a clip of the paper that con- 

 tains only 5 060*000 71 of a grain of gold if we place by the side 

 of that clip for comparison a piece of the same kind of filter- 

 paper upon which gold has not been deposited. Some idea 

 of the almost imponderable quantity of visible gold thus dealt 

 with and accurately measured off for experimental purposes 

 may be realised when it is considered that a grain weight 

 stands about halfway between this weight and a ton weight. 



By using this delicate test-paper the accuracy of Professor 

 Eglington's assertions as to the solvent property of alkaline 

 sulphides upon gold is easily and quickly to be confirmed, and 

 I have even observed by the same test a very feeble solvent 

 power of warm sea-water, also carbonate of soda, upon the 

 same metal. 



I hope to take this subject up again soon, and give the 

 results of further experiments I intend making in connection 

 with it. 



