354 jD^' P^rdval on the Fur/ails 



was held by chemifts, in the time of Sir Ifaac 

 Newton, to be apyrous, and could not be fuf- 

 fpedled, from any of its known qualities, to be 

 of an inflammable nature. Yet this vigilant 

 philofopher did not hefitate to confider it as an 

 un£luoiis coagHlum, folcly from its poficfTing a very 

 high degree of refradlive power on the rays of 

 light. For this power he found to depend chief- 

 ly, if not wholly, on the fulphureous parts of 

 which bodies are compofed. Late experiments 

 have confirmed tliis opinion ; and fully proved 

 that diamonds conHfl: almofi: entirely of pure 

 phlogiflon, fince they are capable of being vola- 

 tilized by heat in clofe veflels, of pervading the 

 moft folid porcelain crucibles, and of being con- 

 verted into aftual flame. 



The accuracy of this inference is a ftriking 

 proof of the importance of judicious and compre- 

 henfive analogies; and of the advantages refult- 

 ing from the mode of reafoning by induflion. 

 For, to ufe the words of Sir Ifaac Newton, 

 ** though the arguing from experiments and 

 ** obfervations, by induftion, is no demonjl ration 

 ** of general conclufions, yet it is the bed way 

 *' of arguing, which the nature of things admits 

 " of; and may be looked upon as fo much the 

 " ftronger, by how much the indudlion is more 

 " general." This improved fpecies of logic 

 was firfl; recommended and introduced into 

 phyfics, by Lord Vcrulam, who, at a very early 



period 



