I lo Identity oftht Diamond and Carbon, — Air Vault. 



plunged into water. But I did not fucceed when I employed pieces of nails Inftead of 

 filings ; for the nails remained unmelted and foft. I propofe to make fome experiments 

 on the fufion of iron with earths, and to analyfe the produ£ls, in order to learn whether 

 fuch a combination can take place, 



I (hall conclude by relating a new experiment, to which I have fubje£ted the diamond, 

 by which the identity of this fubftance with carbon is dill farther confirmed. 



Having prepared fome pure oxide of iron from a folution of the fulphate, by precipita- 

 tion with cauftic ammonia, I mixed a fmall quantity of it with one fourth of its weight of 

 diamond powder, prepared in the following manner : 



The diamond being reduced to powder in a flcel mortar, was boiled in muriatic acid, to 

 dilToIve the iron which might have been abraded from it. After proper edulcoration, it 

 was heated in a muffle to burn off the carbon of the fteel which remained after treatment 

 with the acid, and which rendered the powder of a grey colour. I obferved the coaly 

 matter take fire at the edge of the heap of powder next the ftrongeft heat, and gradually 

 fpread itfelf, till at laft the whole appeared as if burning. The glow through the powder 

 ceafcd foon after, and on removing it I found it perfedlly clean and white. From the 

 diminution of the original weight of the diamond, I found that a part of it had alfo been 

 confumed. 



The mixture of oxide and diamond powder was put into a Cornifli clay crucible, and 

 cxpofed to a pretty ftrong heat for half an hour, after which the oxide was found to be 

 reduced into a metallic button of cafl iron. 



Another portion of the oxide of iron ufed in this experiment, was not reduced when 

 placed in the fame circumflances without the diamond. 



III. 



Account of certain Phenomena obferved in the Air Vault of the Furnaces of the Devon Iron 

 Works * ; together with fome pradical Remarks on the Management of Blajl Furnacesi 

 By Mr. jfoufi Roebuck, in a Letter to Sir James Hall, Bart-f. 



SIR, 



X HAVE examined my naemorandums, concerriing the obfervations I made en the con- 

 denfed air in the air vault of the Devon iron works, near Alloa ; and, according to your 

 requell, I now tranfmit you an account of them; and alfo of an experiment I made, when 



• Thefe iron wrorks are on the banks of the river Devon, which runs into the Frith of Forth near Alloa, 

 They are 3 miles from Alloa, and S from Stirling. 



f Communicated by him to the Royal Society of Edinburgh, and inferted in the fifth Vol. of their 

 Tranfaftions. 



It was omitted to be mentioned, that Sir James Hall's paper in our two laft Numbers is inferted in the 



fame volume. 



» partner 



