246 DR BROWN ON THE PRODUCTION OF SILICON FROM PARACYANOGEN. 



like this, is to indicate the scale of operation on which the process has been tried, 

 and found sufficient. 



It must now be added in conclusion, that in experiments described in this 

 section as well as some of those previously mentioned, the carbon of the ferrocy- 

 anide of potassium is not the only element which seems to undergo transformation. 

 The loose partially aggregated substance like spongy platinum, which is left un- 

 dissolved during the action of water on the red matter in the crucible, does not 

 present the characters of iron or any of its oxides, but possesses, so far as I have 

 yet examined it, all the characteristic properties of the inferior oxide of rhodium. 

 In particular, the metal which may be extracted from it has the colour and infu- 

 sibility of rhodium ; it does not undergo any change whatever on being acted 

 upon by the concentrated or diluted acids either with or without the aid of heat ; 

 it is not corroded even by nascent chlorine ; but it becomes oxidated when heated 

 in contact with the air ; and, when it is projected in powder into melted bisul- 

 phate of potassa, sulphurous acid is given off, and there is produced a yellow 

 salt, wholly soluble in water. This subject I have investigated in its details, and 

 intend to make them public ere long. At present it appears to be necessary to 

 mention the facts in a general way, lest the occurrence of them should embarrass 

 any one who may be induced to revise the researches which form the main object 

 of this memoir. 



Such are the experiments which have been made on this case of elemental 

 transformation. It must be confessed that the results which have been obtained 

 are of a kind, not only so unexpected, but so directly contrary to the doctrine of 

 chemical affinity, which has been entertained ever since the conception of the 

 force productive of combination was first expressed by that term, as to warrant 

 the scepticism of men of science. In truth, although I have performed the act of 

 transformation more than a hundred times, it has always been with fear that the 

 products of the several processes have been examined ; but nature has, in every 

 instance, either disappointed my apprehensions, or rendered apparent failures 

 both intelligible in themselves, and confirmatory of the general initiative of the 

 inquiry. Accordingly, it is with some confidence that I solicit the repetition of 

 these experiments, although I will await the issue of this appeal to the incorrupti- 

 ble judgment of experience with anxiety proportioned to the earnestness with 

 which I have pursued the investigation. 



HADDINGTON, 20th May 1841. 



