WATER. 223 



(m.) Alcohol is turned into acetic acid and water, by the action of 

 the sulphuretted oxide of platinum ;* the same effect is produced by 

 the black powder which zinc precipitates from the platinum solution. 



(n.) Several metals act in a similar manner upon mixtures of oxy- 

 gen and hydrogen ; among them, palladium is the most effectual ; 

 this metal, and iridium inflamed the mixed gases at common tempe- 

 ratures, and gold and silver acted efficiently at a heat below 212, 



Modes of preparing Platinum sponge. 



(a.) According to my own experience, when common crude gram 

 platinum is dissolved in nitro-muriatic acid, and precipitated by muriate 

 of ammonia ; this orange precipitate being collected by subsidence, may 

 be partially dried in a Wedgwood's or other dish, and then transfer- 

 red into a platinum crucible, which may be gradually heated in a 

 little earthen furnace, till the fumes of muriate of ammonia cease 

 to appear. The cover of the crucible may now be put on, and the 

 whole buried in burning coals, which may be blown by hand bellows, 

 both above and below, until it is fully ignited ; it need remain in this 

 state not more than two or three minutes, when it may be withdrawn 

 and cooled. 



(b.) The orange precipitate maybe thrown upon a filter, the filter 

 dried, and introduced directly into the crucible. A greater division 

 of the platinum takes place in consequence of the mixture with the 

 carbon of the burnt paper, and causes the platinum to ignite more 

 readily in a jet of hydrogen ; neither is there any waste of the pre- 

 cipitate, f 



(c.) If a stream of hydrogen from the compound blowpipe, or 

 other jet, fall upon the sponge, it will be ignited, and the hydrogen 

 will take fire.J 



(d.) If the oxygen be let in at the same time, or immediately af- 

 ter, the mixed gases are instantly lighted with a slight explosion. 



* Procured by precipitating the muriate of platinum by sulphuretted hydrogen-. 



t The above circumstance was observed in the laboratory of Yale College, by Mr. 

 C. U. Shepard, and noted Feb. 17, 1827. In the Journal of the Royal Institution, 

 for April, 1829, it is mentioned that Mr. Pleischel recommends that a piece of paper 

 be three times immersed in the solution of murrate of platinum, and then burnt, which 

 leaves the platinum in the best state for producing ignition. The Editors of the Jour- 

 nal say, that a little of the ammonio-muriate of platinum being heated upon platinum 

 foil, in a spirit lamp, with the mildest heat that will dissipate every thing volatile,, 

 the platinum will be left in a fit state to inflame a mixture of oxygen and hydrogen, 

 at the lowest possible temperature. 



Dr. Webster recommends dipping a cotton cloth in the solution of the muriate of 

 platinum, and then burning it to tinder, which, if kept dry, will ignite as readily as 

 the sponge. 



t This contrivance is so good a substitute for the complicated, although elegant in- 

 strument of Volta, in which a jet of hydrogen is fired by a spark from an electropho- 

 rus, that I have not thought it best to give a drawing and description of this instru- 

 ment, both of which may be seen in Dr. Hare's Compendium, p. 65. 



