78 On Cadmium. — Patents. 



liigh. The following is an outline of the process by which 

 it was isolated. 



Upon the slag, when pulverized, nitric acid was digested, 

 until it ceased to exert any further solvent energies. When 

 filtered, the solution was nearly neutralized, and suljjhate of 

 soda added, while any precipitate formed. The precipitate, 

 which was sulphate of lead, was collected on a filter. To the 

 filtered liquor caustic ammonia was added, which at first threw 

 down a copious precipitate ; the greater part of which was 

 subsequentl}' re-dissolved, by an excess of the precipitant. The 

 insoluble portion, which was oxide of iron, was separated by 

 a filter. The ammoniacal solution was submitted, on a sand 

 bath, to evaporation ; by which the oxides dissolved in the 

 ammonia were gradually thrown down. These were then 

 dissolved in muriatic acid, and to the solution carbonate of am- 

 monia was added. A copious precipitate at first occurred, 

 which was considerably reduced by adding the carbonate of 

 ammonia in excess, in consequence of the property this salt 

 possesses of dissolving the oxide of zinc, which was present in 

 considerable quantity. The undissolved residuum, when well 

 washed, was re-dissolved in muriatic acid, and then introduced 

 into a platinum capsule, containing a slip of zinc. When exa- 

 mined next day, the bottom of the capsule was found lined with 

 a dark lead-coloured metallic coating, which adhered so firmly 

 as to admit of being repeatedly washed with distilled water 

 without being displaced.' This experiment, as is well known 

 to chemists, was first made by Dr. Wollaston. It was again 

 dissolved in a drop of muriatic acid, and a small quantity of 

 the solution put in a test tube, into which a little hydrosul- 

 phuret of ammonia was subsequently introduced. This threw 

 down an orange precipitate. To another portion of the solution 

 caustic potash was added in excess ; the white precipitate at 

 first formed was not re-dissolved. 



The identity then of this metal with cadmium is fully es- 

 tablished — by the solubility of its oxide in ammonia ; its in- 

 solubility in carbonate of ammonia and caustic potash ; the 

 colour of the precipitate with an alkaline hydrosulphuret ; and 

 the peculiar appearance of the metal when precipitated by zinc 

 upon the platinum capsule. I may also observe, that a minute 

 portion of the oxide, examined by the blowpipe, presented 

 the well known characteristic properties of cadmium. — Dublin 

 Phil. Journ. 



LIST OF NEW PATENTS. 



To J. J. Saintmare, of Belmont Distillery, Wandsworth Road, Surrey, 

 distiller, for improvements in distilling, — Dated !:?yih June 1825. — 6 months 

 to enrol specification. 



To 



