37Q 



A little silver 

 lost. 



Reduction by 

 carbonat of 

 potash unad- 

 visable. 



Ture potash 

 preferable. 



0age*« method. 



To detect any 

 fiiuriat left un- 

 decomposed, 

 expose it to the 

 sun. 



Excellence of 

 this method. 



ON SILVER. 



parts of lead are a great deal too mueli. The muriaV 

 which I suppose to be melted, should be enclosed in a 

 sheet of lead twice its weight ; the lead having been pvew 

 viously reduced from acetate of lead ; and subjected to 

 cupellation. Thus 73 to 74 hundredths and a fraction 

 will be obtained : in four operations I could not once get 

 75 and a fraction, which is the real quantity present; a. 

 little silver therefore is lost. I know not whether the 

 muriat of lead which is volatilised contributes to this. 



Some recommend the reduction of the muriat by means 

 of carbonat of potash. This method is troublesome, and 

 exposes to considerable loss, on account of the swelling 

 up, running over, and the largeness of the crucible that 

 must be used to avoid this even with small quantities of 

 the muriat. 



Pure potash is preferable, < since the reduction takes 

 place without any swelling up ; but for large quantities 

 this mode is expensive. 



Having had more than a pound of muriate, arising from 

 the repeated precipitations that there is occasion to make 

 in a laboratory, I preferred the following method of 

 Sage. 



This consists in boiling the muriat in an iron pot with 

 a few pieces of iron and some water. The separation 

 takes place very speedily. The liquor, which is a solution 

 of muriat of iron, is to be thrown away ; fresh water 

 added ; and the mixture occasionally shaken. The silver 

 will be obtained in» powder, which requires only to be 

 washed, and melted with a little nitre and borax, to free 

 the silver from a little remaining oxide of iron. If you 

 would satisfy yourself, whether the muriat be entirely 

 decomposed, it will be sufficient to expose the powdered 

 silver to the sun; for if any muriat still remain, the light 

 will give it a violet hue, and gradually darkenit. 



To judge of the merit of this process, I made the follow^* 

 ing experiment. 



In a small silver basin I treated a hundred parts of 

 powdered muriat, well dried, with as much iron filings 

 and a sufficient quantity of w ater. The operation being 

 finished, the muriate of iron poured off, and the powder 

 washed, I added IS parts of mercury to collect the silver. 



Th« 



